Abigail Lee…
I think for a person to sin mortally, they have to have full knowledge of what they’re doing. At an age up to 18, I would say it is highly unlikely that a teenager would be judged on the premise that he/she knew what they were doing, fully. I would imagine a long time in Purgatory might be on the cards. I do not know if this stands in Church teaching but could do with being looked at, if not.
Otherwise, there would be no levels of seriousness and accountability.
For example, before I was a believer, not just a Catholic, and did not understood what sin was, I was not as fully culpable for my actions as much as when I did bad things in recepit of knowledge that my actions were mortally sinful.
It is not about deserving, it is about gratitude and ingratitude. If I sin mortally knowing what mortal sin is, then I am being eternally ungrateful.
So again, for a teenager to really understand or grasp what mortal sin is, is unlikely. Hence, why so many Christian young people in Ireland have backed a certain vote to go through, because they are not spiritually aware or awake. And so, are at the mercy of the world’s presumption and blindness, and undeveloped Christian consciences.
Take excommunication. This only stands in the case of abortion if the person who aborted a child was in full knowledge of what they were doing was mortally sinful, or knew what sin was. And that is an
extreme example:
Read the rules! From:
ewtn.com/expert/answers/abortio2.htm
'NOTE WELL To actually incur the excommunication one must know that it is an excommunicable offense at the time of the abortion. Canon 1323 provides that the following do not incur a sanction,
those who are not yet 16,
are unaware of a law, do not advert to it or are in error about its scope, were forced or had an unforeseeable accident, acted out of grave fear, or who lacked the use of reason (except culpably, as by drunkenness).’
So this must also stand then, for what constitutes mortal sin.
By this, although your thread is not about excommunication, using this subject does prove to some extent that there are degrees of seriousness and they are taken into account.
But I would speak to a priest to be sure.