I just watched Planet Hulk. At the end the Hulk ends up with someone seemingly almost as powerful as he is. Are the Hulks (Green, Red, and She-Hulk) able to have children?
Bruce Banner/The Hulk has two children, Skaar and Lyra, through extraordinary circumstances using advanced technology to ensure the viability of both offspring. Could the Hulk have a child with a normal human? It is much less likely for a number of reasons. Given what we know of all Hulks, it would seem on the face of it an unlikely possibility.
Yes, there is the precedent of Bruce Banner, the first Hulk, having had two children but the circumstances were, at best, out of the ordinary.
It certainly does not mean any human could have offspring with any Hulk. Given the radiation dangers posed to any human from long-term exposure, it would certainly be risky even if someone were willing.
There is also the risk of the pregnancy having... difficulties if the child exhibited any metahuman capabilities during the gestation.
Of course we want to explain how Bruce Banner ended up any children. But for that, we need to consider the Hulk's unique circumstances and his son's mother, who is absolutely out of the ordinary. The alien, Caiera the Oldstrong, was no ordinary human and it is the nature of her powers which have made at least part of this possible.
The alien humanoid Caiera the Oldstrong was NOT A HUMAN BEING, i.e. not a member of the genus homo sapiens sapiens.
She appeared to be a completely humanoid alien, supposedly born and raised on another planet, under an entirely different biome, which should have made any compatibility genetically impossible (see astrobiology), but okay, we'll play along...
she happens to be a member of a species that share both a convergent genetic physical structure (looks entire human),
AND has a compatible genetic structure (able to mate successfully with humans) without technological assistance. (This is assumed, not confirmed, since there was advanced technology on some parts of the planet.)
Adding to this she and presumably any member of her species are capable of being biologically-compatible with humans and gamma-irradiated Hulks who are known to constantly emit radiation of one sort or another.
She was also somehow linked to her planet's ecosystem in an as yet undisclosed manner which she was able to pass on to her offspring.
This link afforded her superhuman strength and resistance making her capable of fighting and defeating an even stronger-than-normal Hulk.*
Their son, Skaar while described as a hybrid was supposedly created between two beings with ALIEN bio-physical properties and extraordinary powers and gaining the best aspects of both.
**Her planet was somehow rich with life-force energy capable of feeding Galactus for hundreds of thousands of years, thus potentially sparing thousands of worlds from his hunger.*
Skaar is the progeny of the Hulk and of Caiera the Oldstrong, who conceived Skaar during the Hulk's time on Caiera's home planet, Sakaar. After Caiera's death, and the Hulk's departure from Sakaar, Skaar emerged from a cocoon, appearing to be the age equivalent of a human preteen. A year later he resembles a human teenager, and subsequently, an intelligent adult, in both appearance and intelligence. --Wikipedia > Skaar > Biography
Given these extenuating (and highly unlikely, sorry, Greg Pak) biological circumstances, a woman whose superhuman powers rivaled the Hulk's, resistance to radiation, an unknown connection to a life-sustaining power capable of sustaining the Devourer of Worlds for millennia, all led to the Hulk being able to become a father. It would take similar superhuman or advanced technological support to see another Hulk able to take the plunge into parenting.
- And please don't get me to thinking about the female Hulks whose eggs should be theoretically, at least, capable of being resistant to normal human sperm... I guess the upside is no worries about birth control...
EDIT: In everyone's zeal to talk about Skaar, we have overlooked the other technologically delivered child of Bruce Banner, the Savage She-Hulk Lyra! This daughter of the Hulk reinforces what I have already mentioned, only a society capable of genetic alteration would be capable of using the Hulk's altered genetic structure to produce viable offspring.
Images of Lyra and Jennifer, first cousins and both Savage She-Hulks
Thundra is an extradimensional human warrior from a high tech society in the 23rd century. She has undergone significant genetic engineering and is physically superhuman with strength and durability making her capable of engaging the Hulk in hand to hand combat.
While there is some strength differential, her fighting prowess can more than make up for the difference in their strength. Her daughter Lyra combines the best of her genetics and the Hulk's creating a warrior whose potential is the greatest seen in generations in Femizonia.
Daughter of the extra-dimensional femizon, Thundra and Bruce Banner Lyra was bred and trained on Thundra's home world as its ultimate warrior.
She was conditioned with one vital difference, as her rage increased, her physical might was decreased, a failsafe initated by the Feminzons in order to prevent her from potentially taking over their planet.
Lyra first appears in Hulk: Raging Thunder and was created by writer Jeff Parker and artist Mitch Breitweiser.
Banner and Hulk have fathered four children between them, they're very fertile. Hulk has two sons from traditional methods i.e. mating, Skaar and the lunatic Hiro Kala (a Thanos style evil genius who poisoned Galactus and has the power to move planets). Lyra was produced from Hulk's DNA and Carmilla Black is said to be Banner's daughter although she doesn't have any of the traditional Hulk powers.
There's no reason Hulk and his ex wife (Red She Hulk) couldn't have children (that they are divorced is irrelevant as they had sex post divorce while Hulked up) either in Hulk or non Hulk form nor is there any reason the other Hulks couldn't have children if they mated which would be difficult as half of them are related! The male - female relationships are :
Hulk / Red She Hulk - divorced Hulk / She Hulk - cousins Hulk / Lyra - Father - daughter (test tube)
Red Hulk / Red She Hulk - father - daughter Red Hulk / She Hulk - not related Red Hulk / Lyra - not related
Skaar & Hiro Kala / Red She Hulk - not related though potential step mother Skaar & Hiro Kala / She Hulk - first cousins once removed Skaar & Hiro Kala / Lyra - step brothers - step sister
I'm guessing the last thing any of them need is baby Hulk's running around which is probably why we won't see it anytime soon but I'm looking forward to an issue in which Lyra brings home a date to meet her dad.