I don't think businesses would have a Threshold; family-owned or not.
So, although the family part of a home-run business would have a Threhold, the area where customers are in would not.
Religious businesses also do not have a Threshold.
imho, a Threshold is a place where by the Old Laws, an invitation is required to enter. Businesses, by their nature, have an open invitation, and therefore offer no bar. A church requires the permission of Someone in order to enter, despite being 'open to all'. (Note that some supernatural creatures are capable, although uncomfortable, with going through a Threshold without an invitation.) Even a religious-owned business which is run solely for charity is a business, which invites anyone in.
Now, if there's a separate building where the business is run out of (an old barn, say), and a home, then although the barn has no Threshold, the home certainly would.