There are lots of so-called DNA labs that advertise heavily on the Internet and are in places not well regulated (like Canada), who will gladly take some sucker's $400 and give them a so-called result. There are even some that will test the samples (though there are more that lose them) but they do not count enough DNA markers to give an accurate results. All you have to do is google and you will find lots of complaints against them.
If you have the big bucks and want to be totally sure, test with Ravgen or the DDC. In the DNA/Paternity community we don't recommend any other.
Are you really the husband in this situation or are you the wife who spent the $400 for the crummy lab and now are wondering if their results are wrong? You sound pretty well-informed about timing issues in pregnancy and unusually calm about the situation to be the husband.
Anyway, if you want to be sure, test with a reputable lab, and if you want to be totally sure, test with both possible fathers.
But as RockRose says, nothing about the dates suggests that the transgression produced the child. In fact nothing about the story suggests the transgression produced the child -- it would be highly unusual to the point of almost impossible for an at-home pregnancy test to pick up a pregnancy only 5 days after sex.
Good luck to you both, work on your marriage, that is the important thing.
I spoke to a gentleman from ddc today, that helped ease my mind a lot. He stated that he had never heard of a water bottle being able to be used for a prenatal DNA test, and that My wife would have had to have given at least 2, 10ml vials of blood, not a finger stick to go on a card like a sugar test.
He also states that the place would have violated HIPPA law by giving her results via a phone call, and that $400.00 for a test just doesn't sound right.
This makes me believe more and more that she found a shady DNA testing company, and that the results are inaccurate.
It's possible he's the dad - although kind of unlikely.
I doubt the story she's telling you about the DNA test, although I can't understand why she'd lie about that. I don't think a prenatal DNA test can be done with a water bottle - at any rate, it would be astronomically expensive.
I'd ask to see the incoming phone call on her phone from the lab, and evidence that she paid thousands of dollars for a DNA test.
Have her test with Ravgen or DDC. It is more money but the DNA from a finger prick won’t be accurate.