Family lists and grandparents and great aunts that I visited with in our line said he was adopted not really August and Augusta's son. On the back of a picture used for a reunion many years ago it was also noted he was 'adopted' and that came from a great aunt at the time. The family said it was "hush hush" and they didn't talk about it - when that generation was young. I only suspect that he may have been one of the eldest girl's child, or something of that nature, and then the grandparents raised him. But I don't know that for sure. He could have been a son of some other family memebr as well. He did have family resemblance to Tuenge's so that would somehow make sense...and support he was related, but the detail is still unclear in my information.
He is never listed as a brother on all of the obituaries I have of August and Augusta's other children and if he was a brother he would have been listed as he lived the longest of any of them (Albert was the last son of August to die, shortly after Mary in very early 60s). I think I have most of the obituaries or notices - but not all (I do not have Richard's for sure - so can't vouch for that one.)
Emil lived with Richard much of the time when younger after August died until he was married. He was listed as a 'son' to Augusta (the Tuenge mother) in her notice when she passed in 1923 in Pine County. If I ever find other information I will post.