Recently when I visited my relative's house, they had lost a bathroom due to a vaastu reason. Without going into the details, an attached bathroom in one of the rooms was apparently a bad sign, hampering a good event from happening in the family, so went away the comfort of an extra bathroom. When discussing about this to my mom, I said that I can never fathom such a correlation between a house's architecture and a future event. I also told her that, because of things like this, I am made to be very skeptical to believe whatever they say, and added that I wish even she had explained me things in a logical way, instead of attaching a story to correct some mistakes that we kids used to make. Let me give a few examples. You can also add what your parents and grandparents told you.
* No cutting nails after sunset. It means 'dharithiram' (extreme bad luck) for the family.
My explanation: In earlier days, without electricity and the modern nailcutters, it is a highly risky thing to cut nails in dark conditions. So, comes the 'dharithiram' explanation.
* No combing hair (for ladies) after sunset. 'Moodhevi' will enter the house.
My explanation: The same as above. Difficult to search for stray hair fallen during the combing process, so chance of it lying in the house and entering into food plates is high.
* Shouldn't eat just after sunset. That being the time of Narasimhavatham, it is an inauspicious time.
My explanation: It is too early time for dinner, bcos in India usually sun sets at about 6-6:30 pm. An untimely dinner then would mess up the metabolism.
* Lock the backdoor of the house before switching the light on. If not, 'Lakshmi' who enters the house from the front gate would exit via the backdoor.
My explanation: Insects and other small animals living at the back of the house might get attracted to the light in the house and enter. So, better to close the door.
* Don't leave any rice specs on the floor after eating. When the woman of the house cleans the eating place with her bare hands, the left-out rice specs would become thorns and injure her hand.
My explanation: Cooked rice is sticky and it has the tendency to break and get smeared onto the floor while cleaning with hands, dirtying the place. So better not to leave it.
* No eating with hands outstretched and supported by the floor. All the energy of the food would go to the ground via the hand-earth connection.
My explanation: Stretching any muscle of the body makes blood to flow to it. Doing so while eating, when the body requires max. blood to be supplied to the digestive organs would not be advisable. Also, keeping it stretched for long time and unstretching later would make the blood flow back into the arteries, causing an unwantedly painful sensation.
The effect of such stories is that, the rebellion inside some of us makes us to question every religious thing passed on from the elders. That was surely a reason why I am an agnostic now. Having said all that, when I was taking my plate after my lunch and cleaning the place, I saw a speck of rice. While my rational (and lazy) mind said to leave it, as mom would anyway clean-wipe the place, my hand reached for the speck, not to 'hurt' my mom's fingers.