not really. He wasnt serious, and even if he was, if i had a kid, or a student, i would love to see how they grew up to be. In jmans case he wanted to see if he was right about how beautiful. The 18 is more of a refernce to come see him when she grows up. (fully developed)
Even if i am wrong(which is certainly possible) jman wouldnt get freaky with konan. Again he wasnt being serious.