Why are my kids so emotional??

I don't know if I have done something wrong-likely- or they were born this way, but my sons can cry at the drop of a hat!! If Ryne cries then Trey is VERY quick to follow, heck if anyone cries Trey starts hysterically crying. I mean can't breathe, tears flying, burying his head in my chest, screaming crying. Weird!?!? If you look at Ryne and start to talk to him and he doesn't want to talk or is embarrassed he starts whining and crying. Seriously WHAT am I doing wrong???
Stephan and I decided in Ryne's best interest to pull him out of his private 4 year old "pre-school" and put him in state pre-k. His 4 year old class was 3.5 hours and pre-k is 7.5, this is a HUGE transition for Ryne, but we figured we would start the transition now rather than wait 'til he was in kindergarten (which is 7.5 hours also.) I mean he is going to have a lot of changes when he begins kindergarten, so the class length difference and larger classes can be tackled now. So far he is doing really well, he actually comes home with "homework" (which is actually something he makes up and does on his own to show his teachers-he really loves schoolwork :), I asked them if I had missed the assignment and they said no, he gave himself homework-he is so cute!!) But the LONG days are taking its toll on him. I know he just needs to get used to it, I just feel really bad. Not to mention they provide breakfast and lunch and since Ryne refuses to eat ANYTHING he is starving when he gets home, to the point he is sick. Talk about feeling like the worst mother EVER!! He just needs to eat more foods, and I am hoping this will make him try more stuff, in the mean time I will just worry myself to death that my son is going to waste away, and cry myself to sleep for being a really bad mom.
Sooooo... when we switched his schools we switched his Karate class, so it was closer. Well his new one is much more intense and disciplined. He was really lost in his first class and just started crying, had to leave the class. I felt really bad for him, but then Trey started to cry and I felt really bad for me. Why are they so emotional??? I Just don't get it...