All my family is obese except me need help (10 point reward)?

-ok so im a 13 year old girl and im 4'10 and weigh 90 pounds so i am normal weight, but everyone else in my family is obese. my dad is 5'8 and 365 pounds my mom is 5'2 and 256 pounds, my 10 year old little brother, who is bigger than me, is 4'10 and is 205 pounds, my 17 year old brother is 5'10 and is over 475 pounds (idk his exact weight cause our scale has a max weight of 475 pounds and when he goes on it, it just reads "WLE", and i read the instructions on the scale and "WLE" stands for "weight limit exceeded" so for all i know he could be 500 pounds) i also have a 2 year old baby sister. i am really worried about my family and were their health is headed. every one in my family eats alot and just sits on the couch. for dinner all my mom makes is unhealthy foods and makes alot of it. i am a very picky eater so i dont eat alot, but the rest of my family is different they can eat everything in site what i eat in a week they eat in 1 meal. especially my older brother. he has a job at mcdonalds and employees get free lunch so he eats maybe 4-5 big macs every day. and also i dont even think my little brother knows that being obese is bad like sometimes i see him playing and squeezing his belly fat one time he said "look at my belly it jiggles like jello" and started laughing. i think because he sees how the rest of our family is obese its normal that he is. i try my best to encourage some exercise but it seems like they dont take me seriously. like a couple days ago i was going to take a jog around the neighborhood and when i asked if anyone wanted to join they looked at me and laughed and said "no thanks" then i asked how about a small walk the only one who went with me is my younger brother, but only 10 minutes into the walk he was complaining about how he was tired and his how his legs were hurting and he was breathing very heavily. i love my family with all my heart but it really bothers me with what they are doing. iv tried to get other people to tell my family that they should start exercising but it hasnt worked. i'v told my older brothers long time girlfriend (who is obese her self) to convince him to lose weight but she tried and still nothing. i and fear the most that my baby sister will end up obese.

when ever i have had a problem my family has always been there to help me now they have a problem and for once i want to help them

i really dont know what to do please help.you could try looking up new healthy reciped of the food that your family loves to eat, so that they would be eating the foods they love, just with healthier foods. also you could try thinking of creative ways to get your whole family active, such as family games such as wiffel ball or going to a park. little things to get everyone healthy will evenually start helping. just keep encouraging everyone to get active and they will eventually come around to the idea! don't give up! you can do it!Its all genetics, its like a box 3 out of 4 squares of the box will be obesity and the other will be normal weight, you got the 25% chance of being regular sized.
Look on the bright side: they will all die soon, leaving you as sole heir.
sorry about this . WEll if your family is going to be stubborn about it and not take you serious then they do have a problem.

They have to want tot change as well you cant make them change because that just doesnt work. Just tell them that you are worried and that you want whats best for them!

Have a dietitian talk to your mother and father .. look up the risks of being over weight on line and show them!!! tell them that what there doing to you and your little brother is unfair !

they need to learn how to eat . There eating junk because thats all they know . your family needs help and its sad that you a 13 should be dealing with this but your there only hope give it all you can :).