Not myself when im around family

I have plenty of friends, im 17 and im just not talkative around my family or at gatherings with family, i can talk to friends and have a good time just fine but whenever im at family reunions ect. I get anxious and find myself sitting in the corner on my phone everytime. I never had any cousins my age to hang with at gatherings, all my cousins are either 6 years older or a lot younger. I feel like if i had cousins my age to hang with i would fit in my family so much more. Im also a way different person around family than i am with my friends.