Is a one-time pad secure if the encryption method is not?
OTP requires a completely random key. That's next to impossible, and human genes are certainly not completely random. This is why OTP's are mainly theoretical constructs.

XOR is the normal way of encrypting using an OTP. XOR is not weak encryption if the key stream is strong. And if the key stream is perfectly secure then XOR encryption is completely secure (for confidentiality anyway).

And no, the messages do not matter. A secure cipher should be secure against known plaintext attacks. That is, different messages or other parts of the message should remain confidential even if part of the message is known.

It's good that you're not offended, because it certainly is a horrible idea.