They generally do not, either due to defects of germ cell formation or just little sexual activity. "As of 2006, three instances of males with Down syndrome fat

They generally do not, either due to defects of germ cell formation or just little sexual activity. "As of 2006, three instances of males with Down syndrome fathering children and 26 cases of females having children have been reported." https://www.fertstert.org/article/S0015-0282(06)03067-6/fulltext https://www.fertstert.org/article/S0015-0282(06)03067-6/full...