SEXUAL INTERCOURSE, REPRODUCTION: HOW DO TWINS HAPPEN? WHY DON’T TWINS ALWAYS LOOK ALIKE?

Posted on March 27th, 2009, by admin

If a woman has twins, do they both come out at the same time? Twins can happen in one of two ways: either there are two fertilized ova or there is one fertilized ovum that splits into two.

Usually a woman’s ovaries produce only one ripe ovum a month. Occasionally, though, a woman will produce two ripe ova at the same time. If both of these ova are fertilized and plant themselves in the lining of the uterus, the woman will have twins. Twins that grow from two separate ova, fertilized by two separate sperm, are called fraternal twins. One may be a boy and one a girl, or they both may be the same sex. They won’t necessarily look alike.

The other type of twins are called identical twins. Identical twins happen when the fertilized ovum splits into two shortly after fertilization. No one knows why this happens. Twins that come from the same ovum and sperm look almost exactly alike and are always the same sex.

When twins are born, one comes out first and the other comes out within a few minutes. In some cases it takes more than a few minutes for the second twin to be born; there have been times when it took a whole day. But, usually, twins are born within a few minutes of each other.

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