This is something I wonder about all the time.
I've spent a lot of time with my WH girls from when they were a day old but I never picked them up or petted them because it seemed to upset them the few times I tried and I didn't want them to be scared of me. I would just sit with them, feed them treats from my hand and they would nap on/beside me.
When they all got bumblefoot last winter (they were about 8 or 9 months old and I didn't realize that the small area of concrete in their pen would hurt their feet) I had to handle them to soak their feet and give them oral antibiotics 2x/day. 3 of the 4 recovered in a few weeks and pretty much went back to the same trust level as before they got sick but the fourth duck, Clementine, was sick for a really long time (infection was resistant to the first type of oral antibiotic so it got worse for weeks even though I was medicating her, then she somehow broke a toe while it was super swollen/infected, then the painkiller the vet prescribed made her vomit, then the bumbles took a long time to heal, so I was treating her twice daily for 3-4 months and had to take her to the vet at least a dozen times, all during COVID and having to hand her off and wait in the car). It was a nightmare and her toe never healed right. Before she got sick she was the bossiest of the ducks towards me (though she wasn't the flock leader) but she's still scared of me now. It makes me feel terrible - like I did a bad job and should never have tried to treat her. She was better by the 4th of July and now in mid-January she is still skittish. It's only in the past month and a half or so that she hasn't said "Bwock" fearfully when I herd all the ducks very slowly towards their carriers to take them to their tractor for the day. (She is the only one of the ducks who has ever bwocked at me and only started saying it after she got sick). A couple weeks after The Last Bwock she started occasionally giving me a little poke and nibble but still won't climb onto my lap even to get peas (her very favorite treat) when the other ducks are hopping up and snacking and she always is on the side of the group furthest from me, though she now runs over with the other ducks when I come to the pen. She is slowly getting less fearful but it has taken six months of patience and not forcing anything.
Anyway, all this to say that if it were me, I definitely won't force your teenagers unless it's medically necessary, and honestly, even then, probably not unless it's a matter of life or death or maybe if you are convinced it will only be a short term medical treatment.