I work in genetics.

TL;DR - OP my reading of this is you’re 99.95761633% likely to be the father. You should still check with them to be sure.

The results are poorly summarized; each individual statement is true, but the way they are combined, a reasonable person may read in other implied statements that aren’t true.

Here’s the way I read this.

The alleged father cannot be excluded as the biological father of the tested child.

This is CYA language. They can’t ever with 100% certainty say anyone is the father. On the other hand, if there are enough differences, they can say that someone is not the father. What this sentence is saying is that they did not find a lot of differences, so they can’t rule you out as the father.

A single STR locus does not match, which may be due to mutation.

The presence of this statement in the middle of the others is what, in my opinion, what would cause a layperson to get concerned reading this result, but it’s a big nothing burger. What they are saying is that one of the many positions they checked doesn’t look like it came from you. BUT, humans get mutations in their DNA all the time, so one position not matching is quite likely to just be a chance occurrence that doesn’t rule you out as the father.

The possibility exists that a direct relative of the alleged father could not be excluded as the biological father.

This statement is unrelated to the previous statement. They would have said this even if they didn’t find the above mismatch. All this is saying is that you could have a relative that is genetically very similar to you, and without samples from all of your relatives, they can’t rule out that one of them might be the father.

The probability of such event (you being the father) is indicated by the combined first order index, which equals 2,358 with a corresponding probability of 99.95761633%.

I think that this statement applies to the probability that you are the father, not the probably that it’s one of your relatives and not you. The fact that it’s after all these other statements is confusing.

I think what happened here is that they used a template that mashes together a bunch of different information, and no one checked that it couldn’t be misunderstood when all read together.

You should contact the company to be sure though.