если не брать во внимание конкретные пары, где разница есть, и значительная (Any past event is historical, but only the most memorable ones are historic. Safire, или classic idiot vs classical music), есть мнение, что the -ic forms are favoured in AmE and -ical ones in BrE; but the distribution is erratic, and is much influenced by the practice of particular publishing houses. Thus in American academic works the shorter forms geographic, geologic, immunologic, lexicographic, and pedagogic are more likely to occur than the longer forms geographical, etc., whereas in British publications the reverse is the case. On the other hand for many ordinary pairs, e.g. comic/comical, ironic/ironical, problematic/problematical, symmetric/symmetrical, the distribution is not governed by geography but by idiomatic or rhythmical considerations in a given context. The New Fowler's Modern English Usage

а что там гуголь считает? словари дают
genetic, also genetical
1. relating to or determined by the origin, development, or causal antecedents of something 2. a. of, relating to, or involving genetics b. of, relating to, caused by, or controlled by genes