Technically no, but only in the technical sense that makes the idea a little useless. Technically, 99% of Down's cases aren't hereditary (it's a spontaneous mi

Technically no, but only in the technical sense that makes the idea a little useless. Technically, 99% of Down's cases aren't hereditary (it's a spontaneous mitotic change), so you don't "improve the gene pool" by excluding it; as far as we know, basically anybody can have a kid with Down's syndrome if the mitotic dice come up snake eyes. (But in the sense most people understand the term? Yes.)