Getting jealous at a relative, let alone a twin, indeed hurts a lot, it's eating at your soul, for years on end, and there's no real solution to it, beside accepting the other and finding something we like in and of itself, not just in relation to that relative. To be one's own person.
And perhaps, accepting love is what could bring Sayo on the level of naturalness of his Hina... being bitter won't help.
The dilemma of natural talent vs hard work is an important one too: I've always perceived myself at untalented and underachieving, but it's also a matter of perspective. Compared to these kids who do quantum mechanics at 12, my IQ might (much) less, but this alone doesn't make them "good" people or even useful, and I'm happy to know things hardly anyone do... to be unique. A sense of purpose helps overcoming jealousy and bitterness tremendously: who cares if you're not the best person to do something... if no one else but you gets and wants to do it ?
I love how yuri makes us reflect on our lives... Yuri is love, yuri is life. Have a good day everyone !