The other night I was breastfeeding our baby and asked DP to pour me some juice. He went to pick up a glass that my DSS had been drinking from earlier, that was still sitting on the table and hadn't been washed since. I asked DP if he could get me a fresh glass and he asked why. I said because it was DSS's glass and hadn't been washed. For the record DSS has had a really bad cold but even if he hadn't I still wouldn't tend to use glasses that he or his DB had been using. It led to DP and I getting into a light-hearted debate because he thinks I'm being unreasonable and he would happily drink from the same glasses as his children. I've said it's different for him because, as much as I love them, they're not my children. DP says that shouldn't matter as we live in the same household and so "we all share germs anyway".
I love DSS but they can be gross wee boys. They need reminded constantly to wash their hands after the toilet. They pick their noses and eat it and do other gross things that wee boys do that are totally harmless but not particularly hygienic and I don't want to share drinking glasses with them. DP thinks that anyone sharing a house with children would be happy to share glasses, forks, etc with those children even if not physically related. Surely it's completely normal not to want to share glasses, cups, cutlery, etc with children that aren't physically related to you?