I don't find him on the California Birth Index under Albert Nash. I will work with combinations of those names and if anything results, I will post it. The only Nevada Birth Index that I am aware of (that is available online) does not begin until 1975. However, I do find a Dan iel Al bert Na sh, born 9/29/1949 in Alameda County, but the mother's maiden name is not Nash. Did you mean the possible adopted dad's middle name could be Daniel - or your nephew could be Albert Daniel Nash?
I do find an Al bert Don ald Na sh, born 1949, who married Joa nne Sad ako Koz uma 9/30/1978 in San Luis Obispo, California. She was born about 1947. He reports as having lived in Idaho as well as California. HOWEVER, I also find, returning with him are: Al bert D Nash (deceased) and Op al Hil da Nash, shows her living in CA in her 90s - quite likely his parents, but I wanted to send this info to you in case you run into his name later.

The spaces that are in the names typed above are there to avoid their names being googled and being directed to this post - IOW, to protect the privacy of any individual (whether they are part of your search or not).