Nosey family................?

why are my mom and sister so nosey?? They're always in my business asking me questions about my personal life between my husband and I....she and .my sister like to know all the juicy details of our life...and when I tell my sister it's none of her business she'll say "I told you about all the things I did with guys" ....she's alot older than me and I''m her little sister I don't want her and my mom to know that because they always think of me as the baby of the family the idea of me even having a boyfriend growing up was a big deal to them let alone me having ...they are so embarring and make a big deal out of it if I kiss my husband in front of them or if he caresses me....why do they act this way I'm not 16 anymore???