I have read in several books all browns/chocolates are from the same 2 dogs!
I have owned a yellow they shed 24/7 365!
Once you try black you will never go back
When I read your post I did some checking of my own.
I don't think it's entirely accurate.
Jack Vanderwyk traces the origins of all chocolate Labradors listed on the LabradorNet database (some 34,000 Labrador dogs of all shades) to eight original bloodlines. However, the shade was not seen as a distinct colour until the 20th century; before then according to Vanderwyk, such dogs can be traced but were not registered. A degree of crossbreeding with Flatcoat or Chesapeake Bay retrievers was also documented in the early 20th century, prior to recognition. Chocolate Labradors were also well established in the early 20th century at the kennels of the Earl of Feversham, and Lady Ward of Chiltonfoliat.
The bloodlines as traced by Vanderwyk each lead back to three black Labradors in the 1880s—Buccleuch Avon (m), and his sire and dam, Malmesbury Tramp (m), and Malmesbury June (f). Morningtown Tobla is also named as an important intermediary, and according to the studbook of Buccleuch Kennels, the chocolates in this kennel came through FTW Peter of Faskally (1908).
You can trace ALL labs back to a few dogs if you want to.
I don't think your concern properly warrants any negative connotations.
My brown dog is a fire breathing retrieving machine.