A few weeks ago, my dad apologized for all the smoking he did in the house back when I was a kid.

“We just didn’t realize,” he said as we watched the little girl on the anti-smoking commercial cough into a room thick with secondhand smoke.

I’ve heard that refrain many times through the years. From my parents. From my aunts. From a ton of reformed smokers. That excuse — the lack of awareness of the dangers of secondhand smoke — has always rung hollow with me. As if my bloodshot eyes and hacking cough weren’t strong enough hints that breathing that stuff in was detrimental.

These days, I am beginning to seriously ponder if I will someday make a similar mea culpa to my son. Dan is 12 and has already played eight seasons of tackle football. He was an aggressive little guy, loved roughhousing, jumping around and knocking into stuff, so as he was heading into kindergarten — and a few months shy of turning 5 — I signed him up for peewee football.

In terms of catching, running and throwing, Danny has done some amazing things playing football. But he is particularly noted for his “pancake” blocks and bone-crushing tackles, the type of hitting that led to such scary nicknames as “Terminator” and “Assassin” from his coaches. My son’s ego feeds off the attention he receives for his warrior mentality.

I imagine Junior Seau experienced the same motivation while growing up menacing whoever crossed his path on the football field. Seau was the warrior’s warrior. The fire in his eyes alone was enough to lead his teammates into battle. In a game dependent on violence for fan interest, Seau was as fierce as they come. He hit — and was hit — for 20 seasons as an NFL linebacker.

Seau’s suicide last week should be a wake-up call for any father who pressures his son to play football and for any coach who pressures his players to play with a head injury. Seau shot himself in the heart. Like fellow NFL great Dave Duerson, who similarly killed himself in 2011, Seau — who suffered multiple concussions playing football — clearly wanted researchers to study his brain for trauma. It’s been documented that Seau had been suffering from depression in recent years. It would be irresponsible not to suggest that his depression was influenced by repeated blows to the head.

Among the institutions in line to study Seau’s brain is Boston University’s Center for the Study of Traumatic Encephalopathy, the research center that found Duerson, a longtime Chicago Bears safety, suffered from chronic traumatic encephalopathy (CTE) — brain damage — due to repeated hits to his head. CTE is not exclusive to NFL players. Boston University researchers found CTE in the brain of an 18-year-old athlete who had sustained multiple concussions.

Pain tolerance is among the core values of football. It’s a game where you’re rewarded for how much you can tolerate. Players — not just those getting paid or on scholarship — will go through anything to stay on the field.

I am certain that I played the last game of my junior season of college football with a concussion I had suffered days earlier during practice. My motivation: I wasn’t going to jeopardize my starting position by letting a headache and some dizziness keep me out of the game.

Awareness of the dangers of head injuries has increased on the youth football level. But there is still precious little medical oversight at practices and games.

Youth leagues need a trainer on-site to evaluate head and other injuries — to determine if it’s safe for a child to continue playing. It is worth the increase in registration fees.

Furthermore, leagues, coaches and parents should limit the amount of full-contact football a child plays during the year. Too many kids on Long Island play tackle football eight months a year.

Ridiculously, coaches begin full equipment practices for the fall season in July. Then, when the fall season ends in November, the indoor football season begins in December with teams registering to compete in for-profit youth leagues that schedule playoff games deep into February.

Hundreds of retired players — including Hall of Famer Tony Dorsett — are suing the NFL for negligence, accusing the league of deception and denial in failing to properly inform players of the link between head injuries and long-term cognitive brain damage.

If players have a solid case against the NFL, then how strong of a case would former youth and high school players have against their leagues, or worse, their dads?

I recall hearing about the first case of ailing smokers suing Big Tobacco in the 1990s and thinking that the smokers had no case, that they should hold themselves accountable for willingly embracing the risks of smoking cigarettes. How completely wrong I was.

Is it so far-fetched to imagine non-NFL players suing the league for selling a product that influenced them to make poor health decisions on the playing field?

Brian Harmon is public relations director at LIU Brooklyn and a former managing editor at Times/Review Newsgroup.