TheOddOneOut
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Most hatchery ISA browns are just RSLs.Not really. That will make red sex links. You'll only get true ISA Browns if you buy them from Hubbard. They are derived from a complex series of crosses consisting of but not limited to RI reds and RI whites.
http://www.feathersite.com/Poultry/CGP/Sex-links/BRKSexLink.html