
I kind of understand what you mean, but it usually doesn't take anything deep to fall in love. Especially because siblings don't usually fall in love with each other. Siblings who do do so because their sense of smell is impaired. An important thing when falling in love is the other person's smell. And normally, with siblings, you smell a smell of home, or even something similar to yourself. It's as if your nose, or your body, knows that this person is home. But with siblings who fall in love, their sense of smell isn't fully intact, so their siblings don't smell like home. That means, mentally, they know they're related and that their feelings aren't right, but for their nose, as their body, it's like a stranger they live with. Of course, not all siblings with impaired sense of smell fall in love with each other. You don't fall in love with everyone you spend time with, but unfortunately, it can happen, and to be honest, I feel pretty sorry for those people.
Tbh i wish they had a deeper reason why they like each other cause its crazy they developed feelings for each other just from that