Translation:I am his younger brother.
私は彼の弟です I am trying to learn kanji in keyboard but duolingo do not accept it.
I though お was used as an honorific to refer to others and or their family members and that when referring to yourself or your own family the お was dropped. Is that not the case here?
Yes. You are right. But 'o' of 'otouto' is part of the noun. not honorific meaning.
And younger siblings are younger than you in your family. So they are commonly called their names or nicknames by family.
People who are not families say '弟さん' and '妹さん' about your younger brother and younger sister. In this case too, 'o' is not used.
I just said "I'm his younger brother" and it said I had a typo in my answer I should type 'I am' what???
Why are "she" and "he" type words included? It makes these sentences extremely unnatural and convoluted as they're more commonly used to mean boyfriend and girlfriend. There has to be a better way to structure these
かれ and かのじょ are not more commonly used to mean boyfriend/girlfriend in my experience, though it is not uncommon to hear them used that way. In fact, I think かれし is a more common way to say "boyfriend", moreso than かれ.
I also don't think these sentences are unnatural or convoluted at all. Rather, trying to find other ways to structure them to not use かれ or かのじょ feels much more convoluted because all the ways I can think of would be heavily reliant on constructing the right context.
Certainly there are many men use '俺（おれ）' and '僕（ぼく）' as 'I'. Though they use '私（わたし）' at the formal situation.
"Watashi" is gender-neutral for polite speech. Informally, men say "boku".
Actually, in my experience, I would say that 俺/オレ (おれ) is much more common for men in casual speech. Older men will even get away with saying it in formal situations.
From what I gather, 僕 (ぼく) sounds somewhat boyish/childish, though it is more likely to be used in formal speech than 俺.
There is no gender in japanese but only girls use watashi. The boys use ore or boku
Kind of actually. Ore is also for princess types and boku is acceptable for girls too. Everyone uses watashi to be polite. It's more complex than textbooks would have you believe but you're off to a good start understanding! You're also correct about the language being genderless. Frankly, these gendered sentences are really confusing
Is this well written? I mean, this sentence makes sense? I tried to say "I am their older sister and I am his younger sister" (I'm in the middle) 私はあなたたちの姉と私は彼の妹です.
あなたたち is a plural "you". For 'they' either 彼ら(for all boys or mixed group) or 彼女ら/彼女たち (all girls).
The と particle is only really used when listing nouns. Listing verbs/adjectives/phrases you would conjugate them into their -te form, and leave the last verb at the end in their normal conjugation. In this case the -te form of です : で. (I believe the -te form is introduced in the Activity 2 skill)
You also don't need to repeat "I" as the topic. It is usually known from context that the topic is the speaker and can be dropped entirely.
(optional "I") (Their older sister) (am and-) (His younger sister) (Am)
I agree with everything you said, but と still works instead of, and is just as natural as, で in this situation, since "their older sister" and "his younger sister" are both nouns.
In this case though there are two separate clauses with "their older sister" and "his younger sister" being used as descriptors of a single person, rather than a list of objects/two separate people, and と can't be used to link clauses.