Some thoughts, no conclusions - i) Tegg is an English surname, an old word for a young sheep. It's assumed to be a metonymic for a shepherd. Some connection.? ii) Tegan, Teegan, Tagan are English language forms of the Irish surname O Tadhgain. Could this be another? iii) There is a Cornish surname Chegwin which sounds similar. It is from the Cornish chy gwyn, meaning "white house".