Parents and Friends of Lesbians and Gays spokeswoman Shelley Argent told news.com.au the provocative clip was angled at mainstream families, and based on the understanding that gay children were "born that way".
"Being lesbian or gay is not a choice," she said.
"It's got nothing to do with culture or parenting skills. It's just the way you are. You're born that way."
Campaign creator Steve Minon, a Brisbane freelancer, said he designed the ad to "get people thinking, and challenge them a little".
"We're trying to point out to any family that marriage equality can be your number one priority, without your knowing about it."
Queensland billboard giant GOA has donated $60,000 of billboard space for the ads and company CEO Chris Tyquin said he will be asking interstate billboard and signage companies to donate space as well.
- nzherald.co.nz