There’s only three reasons to make such a request, geneology, genetic for medical reasons, or he may not think the children are his. If you have nothing to hide and are 100pct certain the kids are his then take the test. Even if the kids arent his or you suspect one or all may not be his he’d have some challenges ahead assuming he listed himself on their birth certificates as being the father. If you don’t take the test you’ll simply fuel the flames with regard to his suspicions. I’d simply take the test and be done with it and if the tests come back the kids are all his I’d sit him down for a serious talk. If you haven’t stepped outside the marriage and the kids are his, I’d really want to know why he felt compelled to push you to this extreme validation. This is pure speculation on my part. If he’s not doing this for medical reasons or geneology then perhaps he’s considering departing the scene and looking for a reason to get out of child support when he leaves. In the alternative and what I would do is simply say (If you have nothing to hide) of course I’ll take the test right after you tell me what the hell this is all about and why you feel compelled to make me do this after ten years of marriage. No matter what he says as his reason take the test but on the condition that he goes to marriage counseling for at least 12 months post test. If he’s got these feelings there are issues that clearly have taken you by surprise and you’ll need some help working this out.