If you are diagnosed with a disabling condition before the age of 22 then when your parents start collecting Social Security you can use their work record to determine how much you will collect on SSDI.

My daughter is on SSDI, she is 27. She was diagnosed before the age of 22, but right now she is collecting based on her work record (working at the movie theater in high school and one internship in college). You need to have a certain amount of income to qualify for SSDI, but if you are very young they don't require as much. But they also don't give you much for a monthly benefit.

When my husband or I start taking Social Security (either old age or disability) then she can use our record and will get more each month.