That's from where Ruby and Yang got the 'boob genes'.
"All I'm saying is that you have boobs bigger than any gir in the entire fucking school!" Raven says, making Taiyang gasp and touch his chest, shocked. Summer and Qrow looked at Raven, agape.
Then they both stare at Taiyang's chest and then blush, making the blonde cover his chest, quickly.
"Don't look at them!" He yells, embarrassed.
They keep staring anyway.