Are boy/girl twins rare?

[Anonymous]

I've heard of identical twins many times but my current boyfriend actually has a fraternal twin sister. I've been introduced to her before. His sister has his same skin color, same gray eyes, exact hair color. She's exactly the female version of him... him in female.

Are having boy/girl twins a rare combination? Rare than identical twins?

[Anonymous]

No, your boyfriend and his sister are fraternal twins and that’s the more common type of twins.

Twins can be fraternal or identical. Fraternal twins come from two different eggs. Normally women release 1 egg each month but sometimes 2 (or more) eggs are released and if both of them are fertilized and grow into babies then that’s fraternal twins. They are fertilized by 2 different sperm so they can be any genders (2 boys, 2 girls or 1 girl and 1 boy) and they don’t look any more similar than ”normal” siblings (they can look similar or not just like any siblings). They’re basically like normal siblinns only conceived at the same time instead of coming from two different pregnancies. Girl-boy fraternal twins are as common as boy-boy and girl-girl. It’s just all up to chance what gender sperm fertilize the two eggs, just as when you have 2 kids from 2 different pregnancies.

Identical twins come from the same egg. So the woman released 1 egg that was fertilized by 1 sperm. When the egg had been fertilized and an embryo had started to grow it split into 2 embryos creating to identical babies. Since they were once 1 they have the same genetic material and will of course always be the same gender.

Fraternal twins is the most common sort of twins, about 3% of pregnancies are fraternal twins. Only 0.5% of pregnancies are identical twins.

[abc3643]

No. My cousins are that.

[Emanon25]

Not really it could happen

[riverrat3]

I dated a girl that had a twin brother