Two of a Kind

Mothers who are four times as likely to have fraternal twins.
1:36 | 01/07/12

Coming up in the next {{countdown}} {{countdownlbl}}

Coming up next:

{{nextVideo.title}}

{{nextVideo.description}}

Skip to this video now

Now Playing:

{{currentVideo.title}}

More information on this video
Enhanced full screen
Explore related content
Comments
Related Extras
Related Videos
Video Transcript
Transcript for Two of a Kind
You see it every day at the mall the playground the elementary school and no you're not seeing double there really is a staggering number of twins and tonight here the new science behind -- stark. Evan and Jason are two of the -- -- a little time. Part of an explosion of twins since 1980 the twin birth rate has jumped 76%. The reason there are more older moms using infertility treatment which -- the chance of twins. But it's also hormone changes in older women causing the release of additional tags. In fact at 35 year old is four times more likely to have fraternal twins and a twenty year old. -- -- Phillips had -- and Jason at age forty she marvels at how her identical boys are so together. Even when apart. And I don't go in and check on them and often times they -- in the exact same position. It's truly amazing it's like sometimes there -- the same person so they'll be sleeping in separate -- Sacramento -- the exact same sleeping position exact same position. And this may sound like baby battle but it's perfectly understandable to this pair. An estimated 40% of multiples have the secret way of communicating in their early years. Twins though aren't carbon copies next we. You don't like chocolate. Can he do different that went right. But there's no denying that special bond. No doubt now and forever. Lisa stark ABC news Bethesda Maryland.

This transcript has been automatically generated and may not be 100% accurate.

{"id":15313459,"title":"Two of a Kind","duration":"1:36","description":"Mothers who are four times as likely to have fraternal twins.","section":"WNT","mediaType":"Default"}