It is going to be difficult to pick out the extra gene if it is your "dinker" project, unless you suspect that it is a gene that is already known and you think you have just a new line. Perhaps a photo of the mom could give us something visual to compare the hatchling to, YB 's pattern can vary from snake to snake and at first glance she looks like a normal YB to me. Only way to be sure is further breeding to isolate the gene.