. >> reporter: doctor shaun david said it's on chromosone15.oth influence areas of brain that include a version two and pleasure from nicotine. >> maybe a company can say we should really look at this gain and see figure maybe there is a new drug to develop. >> reporter: cigarettes kill half the people who smoke. it's the leading cause of death for people of all races, both sexes worldwide. >> if we can eliminate smoking behavior in a small fraction of people it can translate to mom lives. >> reporter: he said that -- that the genes account for about half of smoking. he is a lead author of the study, also a stanford professor of made sun. he said the rest, the other half is environment, advertising, and peer pressure. >> california -- joined other moms for a rally demanding updated laws for potentially toxic chemicals. they call themselves the stroller brigade. the demonstrators traveled to the capitol to try to convince congress to retire the 1976toxic substances control act. they want it replaced a bill to require companies to prove chemicals

we asked shaun harris to come on the program tonight, he said no, but he did sit down with cnn's david mattingly after his sermon on saturday. >> give him a good punch, squash like a cockroach, crack that wrist. what exactly were you telling your congregation to do here. >> i was telling them in strong words that we're not careful. what did i learn this week? be more careful with your words. >> harris says he became the target of angry, hateful messages filled wi ed wited wit and multiple death threats after telling parents how to deal with children and feminine behavior. >> i would say straighten that wrist. >> what about the punch remark? >> it's amazing how punch has been equated to inciting violence against gay youth. that's not what i meant. >> when you said give him a good punch, what exactly did you mean? >> a shove, an affirmation, you see coaches give their blares a good punch, a good slug, it's away of affirming the gender distinctions between a male and a female. >> harris preaches a biblical interpretation at the berean baptist church in fayetteville that homosexuality is a

shaun williams. >> kathryn caroline wright. >> cadet squadron 18. >> joseph edward. >> paul. >> jacob joseph allen. >> dale michael. >> kelly ann. >> willis ryan brown. >> troy. >> kurt. >> douglas. >> rock. >> michael jeffrey hester. >> kyle david. >> rocco francis. >> christie miner. >> richard stewart. >> michael adam. n> kelly an >> joel david short. >> bradford smith. >> craig. >> grant tyler swanson. >> aaron david. >> jonathan fill up. -- still up. >> take lead morgan williams. -- a: morgan williams. >> richard paul yielding iii. >> eric david. >> cadet squadron 19. anthony joseph. >> jonathan alexander davis. >> megan elizabeth i's week. >> -- i is lead. >> amanda michele lse. >> colton james floyd. >> eric matthew. >> caitlin elisabeth glitz. >> chad mossi -- morrison henning. >> alexander james william george hutchinson. >> blake james little. >> maxwell william pitt >> can get -- william. >> kenneth dwight. >> kate nicholas montgomery. >> and zachary james. >> sadra. >> dakota michael. >> robert michael stevenson. >> bennett. >> ellison -- alison. >> grace margaret. >> emily clear ovens. >> hector jose. >> mary catherine. >> james michael. >> have their catherine -- heather catherine watts. >> cadet squadron 20. >> fa