parents talking to me about sex

So I'm 21 years old , engaged, and I lived with my SO for 5months ( we don't live together anymore because he's deployed) so my dad was talking to me about sex it was so awkward, my little sister was there and my mom and we were having dinner, I thought it was funny, they really want to believe I'm still a virgin although my SO is the only person I have ever been with, My sis is 16, my dad was telling me when I start to have sex I should realy take care of myself, go to the doctor and take the pill if I want. My sister shoveling food in her mouth to keep her self from laughing