according to genetics if both parents have the same thing i think it's a 50/50 chance of your child having your disease
unless i read that part of the book wrong
no, no mendelian genetics only applies for
very, very few traits and most of the things that you learned about in bio about gregor mendel and punnet squares and your hair color has now been discredited anyway. turns out, shockingly, that human biology is a lot more complex than just hurr durr 50/50.
remember how every trait comes in a pair of sequences called alleles? There are dominant and recessive alleles, and the presence of just one dominant allele overrides the presence of any recessive allele. For example, "A" is the dominant allele and stands for 'argyle'. "a" is the recessive allele and stands for albino. let's see what kind of situations we can generate.
Obviously: AA = argyle patterned, Aa = argyle patterned, and aa = albino.
First, two AA parents. Since the mother has AA and the father has AA there is no chance that there will be anything but AA, so all the babies are argyle-patterned.
Next, two aa parents. Again, since there is nothing but aa, all babies are albino.
Next, AA crossed with Aa. Half of the children will get AA and half will get Aa, but all will still be argyle patterned.
Finally, the only interesting one is two Aa parents: A quarter of the children receive AA, half receive Aa and one quarter receive aa. That's 25% albino and 75% argyle (although the majority of the argyle children will have the albino allele and could pass it on.)
So why did I feel the need to do this? I just wanted to demonstrate to you that even if mendelian genetics applied to mental illnesses, and ALSO assuming as you did that they'd be recessive, they would ONLY crop up 25% of the time in 25% of possible pairings. That's just a 6% chance of any "defect" continuing through each generation.
So no, people who have mental illnesses should of course be allowed to reproduce.
Poll