Adequate Price Competition and Affiliates

Is anyone aware of a per se restriction against affiliates submitting competing bids on the same procurement?  I checked the FAR and didn't find anything on point.    I am aware of the provisions under FAR 52.203-2 regarding independent pricing.  I'm also aware that GAO will not consider allegations of collusion as a protest ground within its jurisdiction.  See King-Fisher Co., B-228316, B-228309 (Comp Gen 1987) (evidence of collusion may affect a CO's responsibility determination but should be pursued by the DOJ).  I am curious if anyone believes bids submitted by affiliates would create a presumption of collusion.  If so, why would you believe this?    Would your answer be different if the government knew or did not know of the affiliation based on the proposals?

Perhaps another way to ask this is whether only two bids submitted by affiliated companies would provide adequate price competition for purposes of a negotiated procurement.   Thanks.