What do you even say in this situation ?

Me and this guy have known each other for over a year now and we’ve just kind of taken the next step into actually being more than friends and going out and seeing where things go.. The other night me, him, and my daughter (1 years old) were out at a public event and we had a small group of people come over and start talking/picking with my daughter. They started saying how cute she was but they were very drunk and started asking if he was her bio dad. As a first time single mom new to dating.. what the heck do you even say in this situation?! He loves my daughter and treats her as good as he would treat his own but technically she isn’t biologically his?🙁 I don’t really know many other scenarios this situation would happen in I guess but it caught both of us way off guard and it made for a really awkward situation.