Toriyama's a Tail Hater

[Fox666]

According to the Daizenshuu, the second generation of saiyans (Trunks and Goten) were born without a tail (and can transform in Super Saiyan very easy).

[Bussani]

Post got lost:

Well I think the liger would be a better example. If there were children with stripes and without stripes, that would be a similar comparison. However, all of the ligers that I've seen have stripes.

That's because ligers and tiger stripes don't have the right set-up. If tiger stripes were a recessive trait (which they're not) and lions didn't have the recessive gene, no ligers would be born with stripes...unless a lion did have the recessive gene for stripes. But why would a lion have a stripe gene? That's the key to why people say Toriyama's explanation doesn't makes sense: it's not that it's impossible, but that you have to ask yourself why Chichi would have a tail gene.

[DragonBoxZTheMovies]

Funnily enough Freeza loses his tail twice. Once when Kuririn chops it off with his Kienzan and then again when he gets hit by the Genki Dama. To be honest I actually didn't notice that Freeza re-grew his tail when he transformed until recently when I was watching Kai.

[Fox666]

Perhaps Freeza transformations works like layers, so his tail doesn't exactly grow, it just broke off the unnecessary parts.

[caejones]

The problem with the liger example is ... well... Pan.
In nature, when you have a hybrid of two different species, the hybrid cannot produce children.
Since Pan exists, humans and saiyans pretty much have to be variants of the same species.

The best example I can think of to illustrate my point is bloodtype, but I don't think that's quite what I'm thinking of.
Hm, maybe a better real-life example would be ethnic mixing? What does someone with one black and one white parent look like? Some of them come out looking like Barak Obama. Some of them wind up looking like my cousin (kind of an intermediate skintone, with hair that it's hard to judge the length of because it's so dang curly).
Genetics isn't always as clear-cut as dominant/recessive. I have one blue eye and one green eye.

But, really, for the comment about "tails are recessive" to work, tails have to be controlled by more than one gene-pair.
Something like:
T t, where T is a dominant gene that all saiyans have, and t is a recessive gene that all Earthlings have,
And
E e, where e is a recessive gene that all saiyans have, but earthlings can have any combination of the two. Chi Chi happens to be tt-Ee, while Goku is TT-ee. Gohan would be Tt-ee, and Goten would be Tt-Ee.

[Bussani]

The problem with the liger example is ... well... Pan.
In nature, when you have a hybrid of two different species, the hybrid cannot produce children.
Since Pan exists, humans and saiyans pretty much have to be variants of the same species.

To be honest, I only brought up ligers and tigons as an example of two quite different things coming from the same two species, but it didn't really work because it's dependant on the genders of the parents, thus you can't end up with a liger and a tigon in the same litter. That said, it is possible for hybrids to be fertile, as is sometimes the case with female ligers...but as you say, Saiyans and humans seem ridiculously more compatible than that. That's fiction for you, I suppose.

[TheDevilsCorpse]

I think it's easier to assume that Goten and Trunks were born with tails that were quickly removed, since Toriyama has no idea how recessive genes work. Also I know this has no bearing on the canon of Dragon Ball, but didn't Goten have a tail in the credits of one of the movies(the Bojack one if I remember correctly)?

...no? Movie 11 (Bio Broli) has clips of Trunks and Goten as babies at the end, but no tails...