Per the American Board of Medical Genetics
http://www.abmg.org/genetics/abmg/cert-2007/requirements.htm
TRAINING REQUIREMENTS FOR CERTIFICATION
Individuals seeking certification by the ABMG must fulfill all requirements for certification as detailed in this document. For an individual who has a doctoral degree earned outside of the US, Canada or Puerto Rico, or graduate medical training outside of the US or Puerto Rico, additional requirements may pertain.
Doctoral Degree requirements:
Clinical Genetics: MD or DO
PhD Medical Genetics: PhD*
Clinical Cytogenetics: MD, DO, or PhD*
Clinical Biochemical Genetics: MD, DO, or PhD*
Clinical Molecular Genetics: MD, DO, or PhD*
*PhD must be in genetics, human genetics or a related field, as determined by the ABMG.
For applicants for the Clinical Genetics specialty only, training requirements are either:
24 months of satisfactorily completed full-time training in an ACGME-accredited residency program in a specialty (other than clinical genetics) that is recognized by the ABMS (e.g., pediatrics, ob-gyn, internal medicine) and an additional 24 months of satisfactorily completed full-time training in an ACGME-accredited clinical genetics residency program;
OR
48 months of satisfactorily completed full-time training in an ACGME-accredited 4-year clinical genetics residency. (Note: In this instance the 48 months of training satisfy both the graduate medical training requirement and the medical genetics training requirement);
OR
60 months of satisfactorily completed full-time training in an ACGME-accredited combined pediatrics / medical genetics or internal medicine / medical genetics residency. Upon successful completion of all requirements of the combined residency, a trainee is qualified to apply for certification by either or both the American Board of Pediatrics (ABP) and the ABMG OR either or both the American Board of Internal Medicine (ABIM) and the ABMG. Applicants must satisfactorily complete the specific credentialing requirements of each Board to be eligible to sit for the examination of that Board. Certification in one specialty is not contingent upon certification in the other.
BTW Genetics is pretty clinically oriented, esp. when the kids roll in in whatever metabolic crisis they're prone to and the Geneticist is the metabolic expert. Also there are often genetic counselors (with a Masters level education in gentic counseling) who do much of the counseling portion of the work in a genetics dept.