Dual Citizenship (Canada/US), I was born in the US, my father is an American Citizen, my mother is a Canadian?

Hi, Just wondering if anyone knows if I have dual citizenship with Canada and the US. I was born in the US, my father is an American citizen, my mother is a Canadian citizen. I have lived in Canada since 1985, five years old, and since had to apply for a Canadian Citizenship Certificate in order to get a Social Insurance Number, in order to get a Canadian Passport etc. Does the fact that I applied for a Canadian Citizenship Certificate nullify my US citizenship? Please let me know......:)