Hindi Beta: Gender selection is needed
For statements like "I drink", there are two options depending on the gender of the speaker:
Male speaker: मैं पीता हूँ
Female speaker: मैं पीती हूँ
It would probably be a good idea to ask for the learner's gender at the start of the course and explain to them how that affects the verbs they use.
Else our users will have embarrassing moments when they try to apply the lessons in the real world.
This kind of issue is also common with other languages such as French and Italian where adjectives and past participles agree with the subject. In Hindi, it is even more ubiquitous and thus more problematic, even though the voice over mitigates the issue. I think it can probably be addressed in duolingo across all affected languages.
Having said that, it is not that obvious to implement, as the goal of learning is both to speak, and understand others. It is important to understand all forms no matter what. Also, the conjugation mechanics is the same on the third person, so that the a vs. i distinction is still being learned with the first names (Peter piita hai, Julia piiti hai).
A number of languages taught on Duolingo have issues like this, when not directly in the verbs, then with adjectives (or even basic vocabulary choices). Duolingo leaves it up to the learner to establish the correct ones in his/her particular case. If in five years, such a system hasn't been implemented for Spanish or French, I wouldn't hold my breath for it for Hindi. As far as I know, even in the courses with multiple voices, the choice of voice is not determined by the grammar of the sentence. One has to view it as narration.
For these types of sentences, I think it would be best to simply specify gender as part of the sentence. For example:
"I am a man and I drink water."
"I am a woman and I drink water."
They're not sentences we would typically use in real life, but that shouldn't be a problem. At least it's more realistic than "I am an apple."
Would you have wanted to do such a thing for verbs and/or adjectives in French, Russian, Ukrainian, Spanish, Italian, Greek, etc.?
People already complain more than enough about typing "I am a man" / "I am a woman" and that's without its being artificially included in every sentence with "I."
Including the info in the hints in the early skills and mentioning it in the Tips and Notes (which it now has been, cf. Basics 2) seems sufficient to me.
It's good to know the difference but it's also good to be able to say both of them. If you're listening to someone of another gender speak Hindi, you should know what they're saying. If you're telling a story about someone of another gender, you should be able to articulate how they would speak. Just because you're female doesn't mean you're off the hook for learning male speech, and vice versa. ;) Plus, this is by far not a Hindi exclusive feature. French has a huge tree and millions of learners and was one of the first languages implemented, and it still doesn't have anything like that for its gender system.
It would be helpful to know not only that words change depending on relationship but also how they change. Practice with all of them would be best so you don't get confused by different forms of address and words that you might hear.
As far as I understand, Hindi has language rules about how a speaker has to talk depending on the situation, their social status, age, gender and relationship to the listener and then vice versa.
This is where written tips and notes would be very useful. Learning what we need to use and what to avoid would be up to us.