already posted studies and references that support this, but asking you to educate yourself is a fool's errand.
It's folks like yourself that make this issue so problematic, and why others need to stand up to such bias.
As for the Downs Syndrome reference...it's a good one, because it is an excellent example of how a Liberal/Progressive family (the Kennedys) stepped up and actually did something that made a real positive difference in the lives of families with marginalized Special Needs kids...I'm old enough to remember when they were marginalized and suffered the slurs and neglect that used to be thrown around, before people stood up for them. What's the last example of conservatives stepping up to protect and assist a marginalized group in America?...and don't say there never was a need...As for myself, I'm very close to a family at our church that has a DS daughter...she and I are also very good friends...when she was younger, as soon as she saw me come in for Mass, she'd run to sit in my lap...so, don't try painting any false pictures.
You have absolutely no leg to stand on with this issue...the GOP can't seem to foment enough hate and divisiveness...and, it's getting worse...