I'm still unclear although it sounds the same as what I said before only one generation back.
Your parents have transferred the properties into the names of their four children (including you) but have retained the right to the income. Is that it?
If so, as I said above, there are CGT implications (on the transfer of the assets) and IHT implications if these were "gifts with reservation of benefit".
If your parents have retained the right to the income, I hope they have been declaring it else they could be in serious trouble with HMRC over tax evasion.