So two of my older cousins (about 10 years older than me) are getting married which is a total surprise to me cause I didn't even know they liked each other. They are first cousins first of all, and my parents don't like to speak about the topic especially the children part. What is the chance that they're children will have a birth defect? I searched a bit online and what I got were figures ranging from 4% to 70% (LoL), so which one is true? and how would you feel if you learned about your cousins marriage? (btw, It's legal here for first cousins to marry) Wikipedia states the risk is about the same as a woman over 40 having children (about 4%)
Most Helpful Guy
Genetically nothing wrong with marrying a first cousin. It can actually lower some risks, because certain genetic combinations can not play together very well. Things like blood types and the like, much safer with first cousins. They are close, but not "too close", and generally have a slightly higher fertility rate. There are some Middle Eastern countries where 1st cousin marriages make up over 50% of all marriages. Wouldn't work out too well if there was a huge risk. Problems will arise with repeated cousin marriages though, as you will start to get more serious recessive traits bubbling up.
You get a lot more problems in lineal cosanguinity, people related to each other in a line: grandparent - parent - child - grandchild. That can cause big problems, and is illegal pretty much everywhere as far as I know.0