We have one young toddler daughter and are pondering when (and if) she should have a younger sibling -- and what age difference might work best for both of them.

For many (most) parents, what works for them is a major factor, but I have gone to a huge effort to prepare such that I'm ready to make whatever sacrifices I need to do what's best for my kids. I don't mind broadening the answers, but this question is specifically about the kid's angle.

There's a huge amount of soft "opiniony" discussion of this stuff in various media, but I'm more interested in whether people know of any really scientifically solid research that you think is useful to know (for example, data on stuff like 'success', not personality profiles); and what specific personal experiences people have that illustrate difficulties (the less obvious/cliché the better) of certain age differences.

(In our case, they will probably be primarily homeschooled... that probably changes some things, but the responses do not have to be limited to our situation.)

Do you have any siblings? Or children? What are the age differences? Can you reflect on any specific problems in your experience that an empathic parent might want to take into account?

  • 8
    My kids are 17 years apart. They have NO problems whatsoever!
    – Darwy
    Commented Jun 12, 2011 at 18:15
  • @BBM - I don't know if there's any solid research (so I'm asking), and you're right that success can be defined many ways... I'm receptive to any and all: academic level, income, happiness, philanthropy... I want to learn anything that's known.
    – Kilo
    Commented Jun 13, 2011 at 19:06
  • 4
    You are overthinking the matter. Good parenting will produce good children regardless of the spacing, and vice versa. You want another child ... have another child. The last thing you want to do is make it about the other child(ren).
    – tomjedrz
    Commented Jun 14, 2011 at 5:30
  • 2
    @Darwwy - Thank you for addressing the question that was asked! @EveryoneElse - I'm not asking for random, unsubstantiated opinions (you can post those on yahoo "answers"); nor suggestions to change the point of the question (clarification requests are ok). Do you have any actual experience or data that relates to the actual question that was asked? If so, please be specific about what age differences you have experience with. (If you have something you're just itching to preach or start an argument about, please do that elsewhere.)
    – Kilo
    Commented Jun 14, 2011 at 6:03
  • 1
    @Kilo: I don't have siblings. My personal experience as a parent of 1 child is that an exhausted parent, which tries to sacrifice his time and his own needs to the "best" for his child also sacrifices the wellbeing of the child and the whole family. So, IMHO that is the kid's perspective: "I want/need satisfied parents which also have a life of their own." And my experience as a scientist is, that "scientifically solid" research is hard to do already in the natural sciences. So I doubt that you can objectively measure 'success in life'. Thanks for reminding me the FAQ.
    – BBM
    Commented Jun 14, 2011 at 21:34

14 Answers 14


I'm 27 (and male); my two sisters are 25 and 16. I'm speaking from that experience, and from observation of other sibling-sets I've known well.

Basically, I'd say that two kids who are close in age will be in constant interaction with each other, while kids who are farther apart will be more distant.

Closely-spaced kids move in similar fields and circles - they're likely to be in the same school in the same time; to demand attention in similar areas at the same time; to constantly compare themselves to each other. The huge pro here is that this gives them a constant companion; the huge con is that it can also give them a constant competitor.

I know I spent a lot of my childhood playing with my sister; we're very close, and have always been mercifully spared the typical sibling-rivalry issues. I've seen vast variety in terms of relationships between close siblings - everything from "bestest buddies" to "oh, that guy?" to "grrr I will not sit in the same room with you." I really don't think there's any way to predict where on the spectrum any particular group of siblings will fall - but I think that's the spectrum to be looking at.

The more distantly-spaced the children are, the less this will be true. With a wide enough age gap, you'll have less of a "close siblings" relationship and more of a clearly imbalanced "assistant caretaker" relationship. This removes a ton of the potential conflict in childhood and teen years - but later on in life, these siblings might not feel as close to each other, or know how to relate well to them. I'm very close to both my sisters - but I was babysitting my younger sister through high-school, out of the house when she was in elementary school, and married before she turned 13. So even though in theory a 27-year old brother could have a close and evenly-balanced relationship with his 16-year old sister, and even though in just a couple of years we'll both be Semi-Responsible Adults, our relationship is informed by a ton of time when that wasn't the case.

If what I'm saying here rings true to you, bear in mind that I'm talking about small gaps vs. big ones, rather than precise numbers. If you're debating between a 2 year gap or a 3 year gap, that's really not enough of a difference to base a choice on. If you're debating between a 2 year gap and a 5 year gap, then that's already a major difference. An easy trick would be this: choose some gaps that sound reasonable to you, and run along the line, figuring out how that gap is likely to affect the kids at every stage. For example, if Junior is born 3 years after Senior:

  • In Junior's infancy, Senior might be too young to be able to play with Junior or interact with him much. He might also be young enough for serious resentment to be a factor, though this would just be phase.
  • When Senior was 9 and Junior 6, you could home-school them both together, but they'd probably need different activities most of the time.
  • If you weren't home-schooling them, they might go to the same schools (some of the time), but they'd be pretty far apart - so probably not getting in each others' ways.
  • When they were 15 and 12, there's probably a lot of stuff they could have fun doing together (games, sports, activities).
  • When they're in their late 20's, they'd be very close age-wise, and could consider each other good friends.

...and so on. You've got a whole slew of considerations; getting a sense of how each option would work out over time might help you choose the considerations that are most important to you.

Remember also that the sibling dynamic is also heavily affected by the number of kids in the family; that should be considered as well. 2 siblings 2 years apart might be in a toss-up between "best buddy" and "fierce rival", but 5 siblings with 2-year-gaps between them might be a rambunctious gang - with more people and a wide range of ages, competition might be less of an issue, whereas getting attention and breathing space might become more pressing difficulties.

Hope this helps :)

  • I just want to share my experience: I have (much) more in common with my youngest sibling (my brother, 10 years younger), than any of my four sisters which are between us. Commented Aug 3, 2014 at 5:48

From the point of view of the mother and child's health, spacing pregnancies is important. The minimal recommended time between pregnancies varies from 18 month to at least 2 ½ years to 3 years.


Chances are, you're not going to find what you're looking for because there are far, far too many other factors to be taken into account in raising kids (home life/family values, life experiences, innate personality, etc).

As others have mentioned, the best time for them is the best time for you, because if you're so exhausted and stressed from dealing with two young children and working, then you're no good to anyone and you're just hurting yourself physically (remember - mental acuity from lack of sleep is akin to being drunk), mentally, and emotionally.

Kids will likely fight and bicker and have issues while they're growing up, no matter what ages they are. They live together, they're going to butt heads, especially since you're planning on homeschooling (where they won't even have as much time apart as kids who go to school outside the home). I doubt you always get along 100% with your spouse, and you picked them.

Instead of getting hung up on their age difference, consider shifting your focus to having your second at a time when you can best meet everyone's needs, so that you can raise them to be good individuals, without killing yourself or ruining your marriage in the process. If their personalities (something you can't necessarily really change) are close enough, they will likely be close when they get older and can get away from each other for a while. If their personalities clash too much, they'll never grow very close in the long run. Either of these cases would happen regardless of their age difference.

Full disclosure - I grew up in blended families. I have two younger blood siblings, two and four years younger than me, one of which I'm close to now, but we didn't grow up together. I initially grew up in a house where the next youngest was five years older than me. Then my mom married a man who had 7 kids, two younger by 3 and 5 years, two 2 and 5 years older than me, and three that were out of the house by the time we moved in (between 8 and 20 years older). I've never met the oldest two, somewhat know the next oldest, and lived near/went to school with the youngest four (their mother had custody).

Also, my mother is the middle of 5. She's disowned her oldest brother, but is especially close to her older sister, and keeps in touch with her younger siblings (2-6 years or so difference between her and each of them). My father is the oldest of three and they're all very close.

  • To try to make this clear... I do not imagine that any number will be perfect; and I am not "hung up" on age difference, nor am I neglecting the effect on the parents... it's just that the impact on parents (and the subsequent impact on the kids) is already obvious to everyone (as proven by everyone commenting on it). What is less obvious is the kids' perspective, so I'm asking for experience (or data) about that specifically. Thanks for the comments on your experience.
    – Kilo
    Commented Jun 14, 2011 at 22:00

I remember reading from a somewhat scientific source that 5 years would be the least problematic. That said, this kind of thing of course depends a lot on the individual case.

My source is a finnish book called, "Luonnollinen lapsuus" (translates as "Natural Childhood"). It is written by an evolutionary biologist Tiina Kaitaniemi, and discusses child development and early age baby care and parenting practices from an evolutionary perspective. The book is very straight-to-fact, and does cite it's sources.

I don't have the book with me right now, so I will later look this information up from the book, and update this answer accordingly.

  • My brother and I are 5 years apart(me older), We had a few problems when I was about 13-15 but now we are working together in business and get on most of the time. I have a tendency to overrule him, but I think that is just my personality vs his, we are quite different in some ways. Commented Aug 10, 2011 at 9:40

Here's one data point I just read in this research item:

birth spacing and reading and math scores

Excerpt: "a one-year increase in spacing improves reading scores for older children by 0.17 SD—which would be three times the effect of increasing annual family income by $1,000."


My experience is with a larger age gap than most of our multi-childed friends have; we have 8.5 years between my son (currently 10 and a quarter) and my daughter (currently 1 and three-quarters). Most of our friends have 2 or 3 year age gaps.

Comparing my experience with theirs, the main thing I notice is that we all have our difficult periods at different times and for different reasons. For some specific examples:

  • they often have to deal with two in nappies at once, or an older one potty training while they have a newborn, whereas my son was fully independent (and indeed able to be a real help) by the time my daughter was born

  • I was plunged back into the world of sleepless nights and nappies and sore nipples after a good long gap, during which I had regained my equilibrium as a person, not just as a parent; whereas they get it all over with in one go (it's like the difference between making two small adjustments versus one large one, in some ways)

  • it's sometimes easier for them to find outings or activities that will interest both or all of their children at the same time, whereas we end up doing quite a few things with one child per parent so we can go separate ways as appropriate

  • they often find their children competing for their attention in the same way at the same time, whereas I can multi-task mine quite well (for example doing a puzzle on the floor with my daughter while answering my son's questions about his maths homework)

These are just a few examples but you get the gist. There are pros and cons each way and while I like my big age gap (the biggest problem has been people assuming that my daughter was a "mistake"!) it may not suit someone else.

I thought I'd come back and add to this answer now that my son is 19 and my daughter is 10.5. Everything I wrote above still applies, with the appropriate adjustments for their ages (I'm no longer worrying about nappies and sore nipples, for example!) They absolutely adore each other, she missed him ever such a lot when he went off to university last year, and who knows how their relationship with each other will be when they're both adults, but it's really very good now.


My wife is 20+ years younger than her next oldest sister. While this is obviously an extreme case, it does demonstrate that there can be too big of a span between children, although obviously this depends largely upon the personalities of the children.

I say this because the middle sister had a fair amount of responsibility for taking care of my wife as an infant, and wound up having a lot of resentment towards her, as well. To this day, it strains their relationship significantly.

The older sister actually at times claims to be "like a mother" to my wife, and sometimes seems confused about what her role now should be (this also causes significant strain on the relationship, as well as upsetting my mother-in-law).

Again, this is an extreme example. However, I would suggest, at the least, having your second child while your daughter is still, well, a child. I have seen similar situations with friends, where the older siblings were teenagers when the youngest was born, and while not all of them had similar issues, my personal opinion based on these observations is that it would be preferable to have the youngest before the oldest becomes a teenager, unless it is a larger family.

  • 2
    My daughter is 20; my son is 3. If anything, I think your wife/SIL's problem stems to their mother - the person who ultimately foisted off parenting of one child to another. My daughter is not responsible for any part of her brother's care - that's my job as his mother. She's offered to babysit if I'd like a 'date night' with my husband, but other than that she has 0 responsibility to his care, as it should be (common sense things aside - if she sees him open the front door, etc while I'm making dinner).
    – Darwy
    Commented Aug 10, 2011 at 12:18
  • Very true. Yes, I agree that the problem stems from the mother, although the responsibility for taking care of siblings is only part of the story. Overall personality plays a much larger part, imo, but then, personality can largely be tied back to the parents, anyway, so the result is the same :) I guess, in the end, the disclaimer "results may vary" applies.
    – user420
    Commented Aug 10, 2011 at 12:28

My wife is 20 months older than her brother and they used to get on togethere really well as children. (I have no siblings).

So we aimed for about 18 months difference and were lucky. Our daughter also accepted really well her little brother (now 8 months old).

Amongst my colleagues it is also a shared opinion that having a daughter 2 years older than the son is the easiest case since she naturally plays the role of a "second mother" for him.

I also agree with the answer by jny about spacing pregnancies. 18 months is already quite exhausting for the mother.

I would add one important thing which seems not be mentioned in other answers:

You have no real control about when you will conceive a child ! We were quite lucky with that but speaking with friends and colleagues the time can vary up to several years.

I have checked for some sources on that (in French sorry) :

Assuming both of you are fertile and you have regular intercourse

  • you have about 25% of conceiving every month
  • about 84% of couples conceive the first year
  • 8% more will succeed the second year

We knew that and did not put too much pressure on our shoulders.


I'm the firstborn. My brother is 3 year younger than me. We spent our childhood fighting. We have another brother and sister - they are one year apart from each other and 16/17 years apart from me. they never fought a day in their lives - perhaps because they're a boy and a girl. Me and my brother never had problems with them - we helped raising them.


The main issues you'll have is that the elder sister/brother will be the focus of the younger one for many years and this grates with the older child. Our 8 year old is really fed up with the 4 year old wanting to do everything with her, I mean everything. We try explaining that she just wants to be like her, but to an 8 year, this is a royal PITA.

I come from a very large family with age gaps of 2 years between all the children. We still knocked lumps out of each other on a daily basis, into our late teens. The Eldest is 14 years older than me, yet was expected to be 'the parent' if the parents were not around. We've never had issues with each other about this. We're also as close now, as we were then, very close now, all of us.

I don't think, per se, that there is an ideal age gap; they will fight, they will resent each other. They are, after all, kids and will naturally think they are being hard done by...


I don't think it's relevant or important for this case, but it may be interesting anyway because it's (allegedly) a scientific study about inbreeding and age difference:

In the German Wikipedia article about inbreeding it reads:

Untersuchungen zeigten, dass Menschen als Erwachsene denjenigen gegenüber eine erotische Barriere haben, die sie in den ersten fünf Lebensjahren gut kannten.

Which can be translated to:

studies showed that grownups had an "erotic barrier" for people that they knew very well in their first 5 life years.

It doesn't link a source, though.

EDIT: It’s called the Westermarck effect:

The Westermarck effect, or reverse sexual imprinting, is a hypothetical psychological effect through which people who live in close domestic proximity during the first few years of their lives become desensitized to later sexual attraction. This phenomenon, one explanation for the incest taboo, was first hypothesized by Finnish anthropologist Edvard Westermarck in his book The History of Human Marriage (1891). Observations interpreted as evidence for the Westermarck effect have since been made in many places and cultures, including in the Israeli kibbutz system, and the Chinese Shim-pua marriage customs, as well as in biological-related families.


From my life, my half sister and I are 8 years apart and my brother and I are almost 6 years apart. That means my sister and brother are 14 years a apart. That is too much of an age gap between siblings. You will have times when your kids feel this big age gap and they cannot connect to one another. Making it a difficult parenthood. However, in the long run we are all friends now that we are in our 30s 20s and late teens. It was only terrible as kids, early teens and beginning adulthood (wait my brother is still a teen) This is because our parents had different rules for all of us and we kind of sometimes got mad at them for restricting us when our older sibling got to do stuff like stay out late. My sister was an adult when I was a teen = different rules. Now I am an adult and my brother is a teen= different rules. So I suggest that no more than 4 years apart and do not do one or 2 years apart because then it will be an attention battle.


My answer is probably closest to that by @Shauna: there are different factors to consider and the answer depends on what one considers more important.

Small age difference of just a few years means that one would have to deal with jealousy issues, particularly when it comes to the older child. It might be also tiring for parents to manage toddler's tantrums while taking care of a newborn. On the other hand, the children of similar age would interact more, engage in similar activities, share friends. The smaller child development is also accelerated by observing older sibling, while the older learns from observing how their parents take care of the baby.

Big age difference when one kids is already in their teens and the other is just born, the older would be more as an extra parent, helping to take care of the child. This is perhaps the least problematic arrangement, but one would have to wait a decade or two before the two kid start really having common hobbies, friends, etc.

Medium age difference is somewhere between the two described above. Jealousy is usually less of a factor when the older kid is 6-7 or older - jealousy is still present, but less likely to result in outright violence or meltdowns.

Another set of factors to consider are purely physiological, regarding:

  • sometimes making a child may take a lot more time than parents expect - it is the nature who decides
  • the age of parents when having the second child - might be especially important for larger age differences
  • the health of the children - e.g., the newborn may turn out to have weaker health, requiring a lot more attention from the parents (this does not necessarily mean having serious health problems, just being sick more often.)

Specific personal experiences:

My brother and I are 8 years apart (we are half siblings). We never had any 'issues', but we also did not have anything much in common until we both had children. At this point my brother was more than 40!

My husband and his sister are 3 years apart. They have a great relationships (as adults), and share many experiences. I am somewhat jealous at my husband and his relationship, and I think it comes from simply having more in common with respect to what you are dealing with.

Growing up, I never played with my brother (except when a baby, apparently he 'kidnapped' me from my mom for ransom). My husband and his sister definitely had times they didn't get along, but the good outweighed the bad.

My father & my uncle are 3 year apart. They played a lot together growing up, especially as teenagers. They are not as close as adults, for many reasons.

My mom her brothers are 2, 5 years apart (2 & 3 years spacing). My mom has a great relationship with her brothers through adulthood, more antagonized when they were little. Due to various circumstances my uncles were in a boarding school, and my grandmother was a single mom, so the family dynamics might be a little different than other families.

A friend of mine's 2 eldest kids are 19 months apart. It was very hard for the parents, but the 2 kids at 8 & 9 are like pseudo twins - they do everything together. They are opposite gender, so who know what will happen when they are teens.

Our kids are 2 years, 4 months apart. They now 3 and 1, and our 3 year old handled the baby great. A friend of mine has the exact same spacing, and her oldest handled it less well. Who knows what will happen when they grow up.

So, from my specific experiences, I would say that it really depends on the family dynamics, but I would personally rather have them closer together than farther apart, and give them a chance at a great relationship by them being able to relate to the same things.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .