Allowing them to breed? That doesn't mean that their children will be handicapped. I know a kid who's real parents had some sort of handicap and he turned out perfectly normal. Retardation is not in the genes (most of the time) it comes from their parents drinking alcohol and smoking cigarettes and doing drugs during labor.
You are correct, handicapped people can have typically developing children, Mentally normal people can have children with mental and physical disabilities.
I agree with your first statement. I am not sure if you are trying to say that retardation due to mothers taking drugs during labor. Have you been through labor? Whether you have or not is another matter.
I welcomed whatever they could give me.
My kids are both A students. There is no evidence that pain killing drugs administered during child birth cause retardation. Most mental retardation is caused by genetic problems or mismatch ie, trisomy 21, fragile X etc. Obviously substance abuse is no good in pregnancy as it will cause at least some damage to the child.
As for people with disabilities, many autisitics live and work among us living very productive lives. Some marry and reproduce like everyone else. It is thought by many that Einstein was autistic. Many people with mild or moderate retardation are gainfully employed and have children and manage just fine. There is no reason why their children would necessarily too be handicapped. They may need some assistance from time to time but that could be true of anyone.
You could become brain damaged in a car accident or stroke. You can't always expect family to jump in and manage the cost of your care so that the rest of society is relieved of the burden. There are no guarantees in life.
Mentally handicapped people can have a lot of potential and much to offer if they are given the chance and proper education. They are capable of much more that we have traditionally given them credit for. There is a man with Down Syndrome in my city who drives a city bus. Many are willing to do jobs that no one else wants to do but are still very essential. No one has the right to write them off and let them stagnate in mental institutions, which by the way, is much more expensive than giving them life skills and job training.
