A BRIEF SUMMARY OF THE PRINCIPAL SCHOOLS OF CRIMINOLOGICAL THOUGHT ON CRIMINOGENIC FACTORS IS GIVEN, AS WELL AS A CONSIDERATION OF CRIME AS CAUSED BY ENDOGENOUS, OR INTERNAL, AND EXOGEMOUS, OR EXTERNAL, FACTORS. THE LAWS OF HEREDITY ARE DESCRIBED, AND THE CRITICAL TIMES FOR THE ACTIVATING OF GENETIC FACTORS ARE IDENTIFIED AS PRECONCEPTION, DURING CONCEPTION, DURING PREGNANCY, AT THE MOMENT OF BIRTH, AND POSTBIRTH. PRECONCEPTION FACTORS REFER TO PHYSIOLOGICAL AND CHROMOSOMAL CHARACTERISTICS OF PARENTS AND ANCESTORS. CHROMOSOMAL ABERRATIONS, WHICH AFFECT CRIMINAL PREDISPOSITIONS, CAN TAKE PLACE AT THE MOMENT OF CONCEPTION. DRUG AND ALCOHOL ABUSE, AS WELL AS ABORTION ATTEMPTS, INFECTIOUS DISEASES CONTRACTED BY THE EXPECTANT MOTHER, AND PHYSICAL OR PSYCHOLOGICAL TRAUMAS SUFFERED BY HER, CAN UNFAVORABLY AFFECT THE FETUS. CAESARIAN DELIVERY AND DELIVERY ERRORS COMMITTED BY OBSTETRICIANS OR MIDWIVES CAN UNFAVORABLY AFFECT THE NEWLY BORN BABY. LIKEWISE POSTBIRTH TRAUMAS AND ILLNESSES CAN BECOME DETRIMENTAL FACTORS IN THE NORMAL DEVELOPMENT PATTERN OF THE INFANT AND HAVE FUTURE REPERCUSSIONS. IN GENERAL, THE CURRENT FINDINGS OF GENETICS AND FORENSIC MEDICINE INDICATE THAT HEREDITY CAN AFFECT DEVIANCE AND CRIMINALITY IN THE FORM OF A PREDISPOSITION TO CERTAIN CONDUCT. THE DISPOSITION MAY REMAIN LATENT DURING AN ENTIRE LIFETIME UNLESS TRIGGERED BY ENVIRONMENTAL OR OTHER FACTORS. THE POSSIBILITY OF HEREDITY BEING A CRIMINOGENIC FACTOR MUST BE TAKEN INTO ACCOUNT FOR THE FORMULATION OF PREVENTIVE POLICIES AIMED AT MINIMIZING THE DEVELOPMENT OF INHERITED DEFECTS. A BIBLIOGRAPHY IS APPENDED. --IN SPANISH.