Grad party

Tonight my ex is having a grad party for my son. We're all invited. It's going to be awkward, but I am determined to go. It's my son's graduation after all. But, my son doesn't really want to have a grad party at his dad's. I asked im why. Well, he didn't want all these people (girlfriend's parents and friends) meet his relatives on his dads side. He didn't want anybody to know that he is genetically related to these people. I couldn't help but secretely snicker.