The article quotes Huckabee as saying "...says the effort to allow gays and lesbians to marry is comparable to legalizing incest, polygamy and drug use.".
The difference is that there is harm to be done by legalizing incest. There is no harm done by legalizing gay marriage.
"Huckabee also told college journalists last week that gay couples should not be permitted to adopt. "Children are not puppies," he said."
WTF? Did anyone claim they were puppies? Does he think gay couples would tie kids in the yard, put collars on them or something? This was an ignorant statement.
The article also said ""I feel homosexuality is an aberrant, unnatural, and sinful lifestyle," he wrote, in response to a question about gays in the military." which shows his ignorance again.
Those 3 descriptions (as a reason for denying marriage or military service) have been laid to rest numerous times.