should i consider this as a hindrance in my practice advice solicitated:i went to a wedding to perfect my mantra recitation and help around in the vedic work say,setting the "havan-kunda" etc.at night on the last day while i was sleeping in the outhouse,my sister was sleeping beside me, well aware of this fact,was in deep sleep,in my sleep i saw an arousing dream and then in a semi awake sate put my arms around her first in a brotherly way,but then lust gripped me,but i immediately retracted my hand and then went to bed..crying...my questions are...will god forgive me for my sin....moreover i did not spill my virya(semen)but i did commit a break in Brahmachari(out of the 8 breaks)so have i lost my rank of a Brahmachari ?????please help me.....(though this queation pertains to hinduism,i feel my Buddhist brothers and sisters can help)
In my opinion, you have not lost your brahmacharya because your action was not intentional because your mind was in partial sleep. In Buddhism, for sin or transgression to occur, it seems there must be conscious intention. 

If you want to train in discipline like a Buddhist, you should never sleep with your sister, let alone with any other female, even your mother, let alone in public, because, for a brahmacharya, nocturnal emission can happen anytime. 

Buddhists do not believe in God. Sexual arousal is caused by chemicals, electrons &amp; hormones and only enlightened beings do not have sexual arousal. Sexual arousal is 'not-self' ('anatta'). 

The error you made was to sleep with your sister. As a brahmacharya, you must not do this because a brahmacharya should no longer behave like an ordinary householder.