If I'd been a conscript, I'm pretty sure I'd have been the guy who got killed by his own grenade.
You're right about the corrosive effects of guilt. There's a little more hope here than in some of your pieces, and that's good.
A lot of people will relate to someone putting a brave face on things when they feel dreadful inside. People have covered the subject before but that's because people keep feeling like that. Glad to see a ray of hope.
Please take this as constructive criticism, as this is good for such a young writer.
Why does he ask "did someone live here twenty years ago?" He would more likely say "who lived here before us?" He must know they didn't build the house themselves, and if not then obviously someone lived there before them. The question is who were they? Mum could say in reply exactly when the last occupants left.
Try 'Father retires to the living room# rather than 'father resigns to the living room'. Resigning refers to quitting a job due to pressure or a crisis, retire can mean leaving a scene or a room voluntarily.
That said, I like your descriptions of nature and the twist at the end is a good one. Keep it up.
This is a good fusion of science and allegory. I see the parallel between seed an immigrant, but there is some botanical truth here as well. Plants many people think are native were introduced long ago by humans, and it has been said 'a weed is only a plant where you don't want it.' There is a risk, in this kind of allegory, of imposing too many human preconceptions on nature. You have avoided that here.
You're not being selfish, its not your fault if your parents are falling out. They're adults and need to accept some responsibility for their own actions. Yours is not the only family where arguments get out of hand, it happens more often than you may think. I get the impression that you havn't opened up to anyone about this before, perhaps other people have similar issues but they too keep quiet about them. You're not alone in having flawed parents.
I don't know all the answers, but laying all the blame on yourself alone is not one of them.
This is a concise and thoughtful piece. Its a good start for a very young author.