Can human beings and jinn inter-marry?

Yes and no. It depends upon how one looks at it. It is a known fact in the Qur'an in Surah Al-Israa' (17:64) that jinn may share with us our wealth and our children. The Hadith of the Prophet  reconfirms this concept when he says
that when a man has marital relationship with his wife, he should mention the name of Allah . He should seek refuge in Allah from the outcast shaitan. Otherwise, shaitan folds himself up in the man's urethra and shall have sexual relations along with him.

Moreover, when a man goes to his wife while she is in her menses, shaitan precedes him. She shall conceive and will bring forth a sterile person (Mukhannath). Such a sterile person is considered to be child of the jinn.