Genetics in real life

I have already seen this happening in a movie, but I did not know that this kind of thing happened in real life. Pretty girl. Pretty girl has a brother that has mental problems. Boys do not think she is pretty - just God knows the reason why. Boys are not interested in her because of another reason. One of the boys said: "Oh, we have to think of some things, don't you agree? She has a brother that has mental problems. I'm worried about having her like my girlfriend and after getting marry with her...I have perfect genes, and I don't want to mix my genes with her ones...if she has defective genes, these genes can be included in my future children. I don't want to take the risk of having kids with mental problems..." This boy said his opinion was the same of his friends - boys that also know her.

I was shocked. In fact, I'm still shocked. I have already knew that men and women seek healthy partners, partners that can produce a healthy offspring. It's our animal feature; we want that our genes be spread over the earth. But I always thought this feature was just instinticve and unconscious. I have never thought that somebody could say that is looking for a partner whose genes are perfect, I mean, I have never thought somebody could say it in a conscious and rational way. I have ever seen this kind of thing in a movie, but not in real life. It sounds so bizarre that we could say it's funny. I have never imagined that those boys could be so worried about the future of their offsprings. That pretty lady will surely find a partner that is not afraid of her defective genes...