However, for a given pregnancy, only the mother's genetics matter. Fraternal twins happen when two eggs are simultaneously fertilized instead of just one. A father's genes can't make a woman release two eggs. It sounds like fraternal twins do indeed run in your family!
Similarly, you may ask, is the gender of a baby determined by the mother or father?
Men on the other hand have an X and a Y. So, each of their sperm carries one of the 2 sex chromosomes, which sex chromosome is in the sperm that fertilizes the egg dictates the baby's sex. This means that dad, although he can't control wether an X or a Y gets to the egg first, chooses you baby's sex.
What determines whether you have a boy or a girl?
Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother's X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother's to make a boy (XY).
How is a boy or girl conceived?
How To Conceive A Boy #2: Male Sperm And Cycle Timing. Because male sperm is the faster of the two, Shettles suggests having intercourse as close to ovulation as possible. If you have sex several days before ovulation, then the less resilient male sperm may die off, leaving more female sperm to fertilise the egg.