안녕하세요!

Let's take this step by step.

If the only thing you know about Genes A and B is

"Genes A and B control for two different traits"

then, you can't really know if they are linked or unlinked.

If you also know

"Genes A and B are both located on the same chromosome"

then, you still can't really know if the two genes are linked or unlinked.

Finally, if you also know

"In regards to the two traits, most, if not all, offspring resemble one or the other parent"

ONLY THEN can you know that the two genes are linked.

Back in the day before we had computer genetic analysis methods,

we could only guess whether 2 genes are linked or unliked by looking at the phenotype ratios of the offspring.

We even used equations that could estimate how far apart the 2 genes were

(developed by a graduate student under Professor Morgan, who first proposed the concept of linked genes)

and discussed how close the two genes were on the chromosome, using units such as "Morgan" or "Centimorgan".

However, nowadays we have much more sophisticated methods of analyzing entire chromosomes,

so we can actually physically see how far apart genes are,

and based on that, calculate the probability of crossing over occuring.

Keep in mind that crossing over is not an "all-or-nothing" event,

because crossing over can occur anywhere in the chromosome.

We can only talk about "probability" that the two genes are linked,

where if the two genes are literally right next to each other and always inherited together

they are "completely linked"

and if there is a large distance between the two, so that the genes are essentially independent from each other,

we call them "unlinked".

Everything in between can only be discussed in terms of "likelihood" or "probability" of being linked

I'm not entirely sure if this answers your question,

but 열공하시고 혹시 또 질문이 생기면 게시판에서 만나요! :D