On edge much? Since you cant tell the Tone of my post, from how i would directly say it to you, i would suggest not assuming that im upset, or annoyed, or any of those feelings.
No, the reason anyone makes that comment most of the time, is because if something is being bred that has a very obvious problem ( in their eyes, everyone feels differently of course, but Generally obvious problem, such as... Oh i dont know, those weird cats with the short legs for example, or silk backs as another visual example) And dosnt give a second thought to the genetic problems on a non visual level, they are considered doing it for the money.
A few random twins here and there, yeah, i can accept that. If it was constant twins, or an obvious reason for you to be trying to breed for more twins, i would look at it differently.
You arent Greedy for the money because you want to make a business out of breeding your animals. One would only consider you to be greedy for the money if you were breeding animals with obvious problems, or traits that could later affect the livelihood of dragons down the line. Things dont have to be immediate, or visible to say there is something wrong.