The studies were made by an austrian monk https://en.wikipedia.org/wiki/Gregor_Mendel
more than a century ago. Autism is obviously hereditary and is running in many families.
There are many studies as well made recently that show siblings and parents of an autistic child are more likely to show autistic signs even too tiny to deserve a diagnostic, just google siblings autism study. The fact that autism is hereditary is running in some families is not a discovery.
I am a carrier of the gene, I have moderate signs of autism and I gave the gene to my son and I get it from my father, one of my father sisters is also obviously a carrier of the gene and her children as well.
When Kanner and Bettelheim were speaking about mother refrigerator as the cause of autism, they were wrong. But what they saw was right, the mothers they met were very modest about their own feelings toward their own child, a typical attitude of someone who is asperger and this was misinterpreted.
When I meet the family of a children with autism, after having several hours with them, It's quite easy for me to guess from who autism is, from the mother, from the father, or from both of them. You are aware about autism as well and you can do the same.
About how breastfeeding is beneficial : http://www.llli.org/llleaderweb/lv/lvfebmar02p10.html