Well my brain is going down this route. (Also I need to distract myself because I got pissed off by something so stupid)
Do you even think that, Gamma Jack was scared of holding babies/Infants or kids?
I mean yes, he can control his radiation because he knows what he's doing, but I'd like to think he cares but babies are fragile to him and honestly he knows he a walking nuclear bomb with a high radiation level.
After all people would assume he doesn't like babies or kids in general, when in fact he doesn't mind kids or babies, he just doesn't want to hold them/accidently giving them radiation poisoning. Again he could control his radiation but I'd like to think he tends to doubt himself, because even though he has his powers underwraps, a part of him fears that his radiation would bleed through causing harm and damage to the kids or infants.
Like a high potential during the Ban/relocations of the supers, depending on the timeline when Violet was born, I'm positive that Jack was terrified of holding Violet when she was born. Because I'm sure that Bob called Simon, Jack and as we already knows Lucius to come see Violet.
Imagine being Jack and seeing your friends holding a baby in their arms, while Jack on the other hand is refusing to hold her, because of one he doesn't know if Violet is immune to his powers or two he's not sure if Violet even has powers at all, to him a baby is still a baby a very defenseless in a cruel, cruel world. But in the end he just smiles but still refuses to hold Violet but does he explain his reasoning to both Helen and Bob?
He just refuses to hold her, he wants to hold her, but every fiber of his body just screams at him what if he hurts her, does some damage to her or the very least cause every lasting side effects to her. He'd be traumatised by what's he done.
So he takes the precaution of not holding any babies at all, it's a fear he takes since again kids are fragile like glass to him.
Although his friends can see how he hesitant and scared he is but they don't push it even though they find it weird as he has control over his radiation they don't understand why he can't just cradle any infant or baby in his arms.
They could see he wants to, as they slight push him to hold a baby in his arms but he tends to let his fears hold him back. He wants to hold babies and children but his fear always sets him back, due to how he could accidentally kill them.
Though I do believe he finally did hold Violet in is arms once, how? Very easy the simple parent. "I need to go real quick"
Either Bob or Helen went "Here" no warning and Jack held Violet in his arms and when I tell you Jack was not okay, he was trembling when Violet looked at him, he was going to cry because Violet was perfectly fine and cradled into his arms just looking at him.
Though when they came back Jack handed Violet back into their arms and rubs his hands together clearly worried since nothing happened but the thought of something happening truly made him worried but both Helen and Bob assured him that Violet is alright, nothing is wrong with her and he didn't hurt her.
It was the most traumatic event he endured but it did heal him from assuming the worst?
Heavens no, it helped somewhat he'll hold a baby for a about a few seconds and be like. "Alright time's up cute kid"
It's progress for him but in the end he'll go back to not holding any babies or kids. Again due to the fear of his powers.
Although it's just a little HC of mine but overall I think it'd be interesting if he was indeed scared of hold kids let alone babies at all. Think it'll haunt him in his nightmares if he ever found out he'd accidentally harmed a baby or kid.