As I mentioned in my 'coming out' post my great grandmother had a set of fraternal twins. Now this great grandmother also had 11 other children. The twins were #7 and #8 in that string of children. So it makes me think, if one were to have enough children aren't you bound to get twins eventually?? Maybe not the SECOND go round? This was my mother's mother's mother. Seems pretty far removed if you asked me....
Just to clarify up front for those not familiar:
Fraternal twins is the mother releasing TWO eggs at once and they both get fertilized by two sperm. Basically two siblings just sharing a womb. Gender combinations can be boy/girl, boy/boy, or girl/girl. However boy/girl is most common. This is also common with fertility drugs (which we did not do) because women are getting more eggs fertilized or the drugs are causing multiple eggs to release (I am no expert on fertility drugs and honestly have no idea bout them so that is all I will speak about that)
Identical twins is a fertilized egg splitting and the twins share DNA. In this case they will be the same gender and never one of each. This type is rare and not hereditary.
As I mentioned in my earlier post our twins are Di/Di. Now these are most likely fraternal but on a rare case can still be identical. We do not know yet, after finding out our gender, if it's a boy and a girl we will know for sure they are fraternal, if they are the same gender we still will not know without a DNA test done after birth.
I had heard that fraternal twins are hereditary and is passed down through the mothers. Although after reading this (NYTimes article: The Claim: Twins Always Skip a Generation ) it points out that a son can get/carry the gene (although not effected since they do not ovulate) and pass it on to his daughter. Also says it's a myth that twins skip a generation.
With that being said... my father's mother had a miscarriage with twins. So does that mean my father had the gene and passed in on to me? Maybe that is how I got the gene??? Through my mother AND father. That would make more sense how I happen to have twins after a few generations without them.
I am also at a higher chance for twins because I already had a child. For some reason this increases your chances....? I am over 30... but not by much (31). Everyone stands a 1 in 30 chance of having twins. This chance for me now goes to 1 in 14 if we decide to try and get pregnant again. Whoa!
"The genes that cause a woman to have fraternal twins are unknown." (source)
So it kinda seems like my question of twins running in the family still remains unknown or at least no the clear answer I was looking for.
One other theory of twins I have is, as you saw with my great grandmother she had a lot of children. And I feel like in the past people were having bigger families. Maybe since now-a-days people are having smaller families and waiting longer to have those small families. God is blessing people with twins to make up fo rthe fact that these big families aren't being created as much as they used to?? Just a theory :-)