I have cousins on both mother and father side na adopted
Yun sa mother side muna
Bale, yun isa older sakin. Kwento ng father ko when he was just courting my mom (extended yun family home) yun cousin ko na si T, lagi daw kawawa, kasi nabubuntal palagi, especially when yun isa sa mga boy cousins ko umiyak, on some perceived slight. Nakukurot pa daw sa singit ng grandma ko. Pero you know what, very nice talaga siya, did not harbor resentment. Happily settled naman siya. She is my favorite cousin, very pleasant and light lang kausap. Magalang pa
Yun isa naman, near my age. Anak sya ng sister ng aunt ko (my uncle is the bro of my mom) yun naman, siguro kasi ibang generation yun, so wala masyado issues, and by then yun grandma ko di naman na ganun ka-terror/commander like

nice din yun, quiet lang. BTW, typical adopted child siya sa chinese, with the hopes of having a child after or something like that
then on my father side naman
naku, this girl S, was so unpleasant when we were kids. Kakahiya man to say, we ganged up on her, kasi talaga maldita nun bata. Pa-spoiled, feeling slighted always (well sometimes, hehe). I remembered, when we were kids, we never play with her, we would escape to another location just so di kami mapilitan to play with her. So childish. but there. But now, quiet nalang siya sa reunions, would always stay in 1 corner. Pero yun pala obvious na adopted siya kasi anglayo ng facial structure niya sa family

Bottomline,
Dapat open sa idea yun family. Kasi the kids can be more brutal (true), adults might resent (money, education, perks, etc). Dapat committed din yun adoptive parents, kasi like dun sa case nung isang aunt ko, medyo neglected yun adopted kid, kasi, well, my aunt is retired and just on sustento-basis sa isang cousin ko, so dun sa adopted cousin S ko, di naman or very liit lang the money being given to her narin.