Family in town

So my parents have come and gone - I am still recovering. Although I was off for 1 week, I really wasn't getting any rest as I was driving them all over the place. I have come to realize that spending a lot of time with my family can be really mentally draining and stressful. At times, it can get really emotional as well. My dad and my 15 year old brother got into a fight because he had deleted all the Grand Canyon vacation pictures and didn't tell my dad. So all the photos he took are gone - my dad was furious. Another time I got into a discussion about Alex's weight. He's 15 and weights 186 pounds! Very obese for his age and no one is taking any accountability for this. My mom enables him by constantly feeding him late at night. "He's a growing boy" is what she would tell me, and I would reply "he's growing the wrong way!" This weight puts him at risk to develop diabetes. I told them that if Alex were to develop diabetes that it would be their fault because they were responsible for him. Sometimes I feel that my dad is too exhausted after a days work to spend the time teaching him the tools to become a confident young man. It's like he went into parental retirement after I graduated from college. The sad thing is, I don't see things changing.