Right. Hence "more difficult" than from saliva. Think about it. Each sperm cell gets a random mix of your chromosome sets. There are 2^23 possibilities. But o

Right. Hence "more difficult" than from saliva. Think about it. Each sperm cell gets a random mix of your chromosome sets. There are 2^23 possibilities. But of course you only need to find the matched pair for each chromosome. So you'd only need a few hundred cells. I'm not a geneticist, but that sounds like a much harder genome sequencing/assembly problem than the fully matched set you'd get from saliva etc.