Why does my grandfather treat me like a kid?

I just want to know because every since i was 13 he's been treating me like a little kid like he gets me so many cheap meals that come with a small drink and small fries and he won't pay for a meal at a restaurant that's more than 5 dollars.Plus for breakfast he gets me a small bowl of cereal and its just not enough.Plus im 19 years old and im 5'9 in a half barefoot and i do work out and my grand father is 6 ft and he's still treating me like a kid like he won't let me do what i want to do like last year when i was 18 he said he was sending 60 dollars for me to have and he said can you handle that much money and i said of i can.Then when he came to visit me and my mom and brothers in las vegas i was just standing and he was patting me on the stomach and i said what.Like my grandma treats like an adult and so does my uncle and my mom and my dad treat me like a grown man but not my grand father.Now on july 16 we have to move to my grandfathers place in cypress texas and i plan on getting a job so i can make some money and move out of his house.So why does my grandfather treat me like a kid?