I responded to somewhat similar skeptical worries about personal identity in my reply to Question 4958. You might have a look there.
To respond to your specific claims here:
(1) Even if we grant that you're "basically a combination of cells created by DNA instructions [that] react to stimuli," surely that's not all you are. In a petri dish we can grow a combination of cells created by DNA instructions that react to stimuli, but it won't submit a question to AskPhilosophers. Not all combinations of cells -- again, assuming that's what you are -- have equally impressive capacities.
(2) Even if "everything [you] say, believe, and do is based on [your] genetic make-up and environment," surely that not all it's based on. You submitted a question to AskPhilosophers at least partly based on your desire to get an answer to it and your belief that this website is one place to go; there's no reason to think you would've done so without any such desire or belief.
(3) Your parents' advice seems to be based on reasoning that launches an infinite regress: you're allowed to admire only those virtues that someone chose to cultivate, but surely a person's choice to cultivate a particular virtue stems in part from some virtuous feature of his/her character, which in turn will be admirable only if chosen, and so on ad infinitum. Why think that our concept of being admirable contains a requirement that's in principle impossible for anyone to satisfy?
(4) When I perspire on hot day, that's simply "my body reacting to my surroundings and determining it would be a good contributor to my overall survival" (if we construe "determining" in non-agential way). But why think that when I donate to charity, that's all that's going on? Charitable donation is much more cognitively complex, and much more reasons-based, than perspiration, and I think the difference makes a difference.