Society does not want disabled people to have children.
Have biological kids? "How could you do that to them? Aren't you supposed to love your kids? You know how bad it is to be you. How could you inflict that on them?"
Trying to adopt? "We just don't think you'd be a fit parent. We've rejected your application. By the way, have you considered sterilization, just to be sure?"
Taking in a kid informally because of their current living situation or lack of? "Are you sure you shouldn't pass them off to someone else? You know you're not as... capable... as the average caretaker. Kids are a lot of work."
Disabled people are not considered to be fit guardians by the mere fact that we are disabled. "Removal rates where parents have a psychiatric disability have been found to be as high as 70 percent to 80 percent; where the parent has an intellectual disability, 40 percent to 80 percent. In families where the parental disability is physical, 13 percent have reported discriminatory treatment in custody cases. Parents who are deaf or blind report extremely high rates of child removal and loss of parental rights. Parents with disabilities are more likely to lose custody of their children after divorce. In addition, prospective parents with disabilities have more difficulty when it comes to accessing reproductive health care such as assisted reproductive technologies, and they face significant barriers to adopting children."
-Rocking the Cradle: Ensuring the Rights of Parents with Disabilities and Their Children (2012, National Council on Disability)