It is a highly subjective area. I do not like to answer subjective questions with "facts". There are no official fixed considerations given for siblings. However, two of the concerns of the Admissions Board are if the candidate is aware of what he is getting into and whether they are probably going to be successful. When an admisssions officer presents a record to the board, he might or might not mention a sibling in an effort to augment one of the above areas. Again, it is what a specific officer might or might not do on a given day depending on many variables.
time2, again I ask what your stake is in this game and why you seem to troll (trawl) behind everyone simply to cause hate and discontent?
The way forums normally work, for those who are genuinely interested in the thread, is that if someone is not sure, they will leave a response which "asks" for clarification, if appropriate. Thence the "I believes", "I thinks", etc. If they are incorrect, someone will surely rectify this.