In The Odyssey, what reason does Odysseus give for not answering Penelope's questions about his background?

Odysseus, disguised as the beggar, attempts a few thwarts
of this question. At first, he just allows Penelope to tell her story and background
which she hopes would help him begin to tell his own story. Fortunately for him, it gave
him time to connect to something she said. Obviously he cannot tell the truth, he needs
to keep his identity a secret to even her until the suitors are killed. But, he did
think long enough to craft a story about the fact that he had run across Odysseus in his
travels. This mention of her husband distracts her enough that she doesn't really ask
for his background again. He describes Odysseus and tells of his safety. This confirms
for her that he is telling truth because he knew details the common person would not
just know about Odysseus, and then he gave her hope. He didn't have a good reason for
not answering her questions, he just skirted them thinking as a beggar he could be
considered a man of little importance.