Read the following premise and answer if the hypothesis is true.
Nana Kwame Abrokwa (born 5 October 1968) is a Ghanaian born German rapper and DJ, performing under the pseudonyms Nana or Darkman / Nana. Nana is not an actual first name, but a Ghanaian title of nobility. His most important achievement came in the second half of the 1990s, when his style was characterized as "euro-rap".
Hypothesis: Nana Kwame Abrokwa did not know how to rap until he was 15. Is the answer "Yes", "No", or "It's impossible to say"? Respond with only the answer and no additional text.
It's impossible to say
It's impossible to say. The given information does not provide enough context to determine when Nana Kwame Abrokwa started rapping.