Miss S, thanks for asking
Radu is talking about identical twins, which (although people do ask me?!) is not the case for my brother and I
Our birth charts are very close; the only differences are aspects to angles and some planets in different houses. Being different genders, the differences in our personality/behaviour/choices can't be separated from the differences in conditioning for male/female children, and/or the way men and women "use" astrological placements (whichever you believe most is fine by me, I subscribe to a combination of the two).
As this is something that has fascinated me no end, I'd like to post my observations. I feel like I've made some mental headway, with help from the forum!
Ok. Personality wise, if you could remove us from our respective "settings" and place us in a neutral setting, I believe we are quite smiliar. We're both easygoing, friendly, intelligent, independent, and quietly ambitious in our own ways. We also both avoid expressing conflict/anger, unless we need to. I think the differences, house and aspect wise, describe the different FOCUS we each choose.
Here is a summary for you
Him:
likes sport, plays lots of it
likes THINGS, new shiny expensive things
owns a new shiny car, that he has detailed monthly
Exceeded $1 million in personal investments/assets this year (!!)
Is in business partnership with our older brother
Programs computers for a job, with no formal training in this area
Hasn't finished his law/commerce degree, because he stopped ot make money
Has only left the country on a cruise ship
(I think this is hilarious)
Got engaged (to someone with the same name as me, gahhh!)
Is generally more conservative and more organised than I am
No interest in astrology, or any of my interests (below)
WANTS: to own his own island
HAPPY WHEN: he's monitoring the strong performance of his business deals
WORRIES ABOUT: personal/family relationships, and being seen as/being too materialistic!
Me:
like writing/art/dreams/astrology/being alone more than him
like EXPERIENCES, all of them, anywhere, and people
Own no car, catch public transport and ride my bike everywhere
Net worth, around negative $5000
Work as an English teacher/Life model/Social research analyst
Currently studying my masters (international development)
left the country at every possible opportunity, lived overseas total 3 years
generally less conservative and more spontaneous than my whole family
WANT: to work for Oxfam/Red Cross/United Nations
HAPPY WHEN: I've been offered a new opportunity in my field
WORRY ABOUT: professional life/being unable to do what I feel I "need to"
His workmates joke about the fact that he's secretly 80 years old. My mum reponded to this joke by saying, "if he's 80, then she (myself) must be 10!!" Hated the comment at the time...the fact that my brother is worth a fortune tends to discourage me, but I just have to remember that being wealthy was never my goal, and if it had been, I could have done it by now. It just isn't!
Main astrological differences:
Him - Sun/mercury in 5H with uranus......Me - Sun mercury in 6H with neptune
Him - MC taurus, IC scorpio......Me - MC Aries, IC Libra
Him - Mars in 2H, Jupiter in 3H......Me - Mars in 3H, Jupiter in 4H
Him - Ascendant square Saturn, Jupiter conjunct 1C (in 3H)
Me - Neptune trine MC, pluto (3H) and jupiter (4H) conjunct IC
There's more than that, but those are the basics that I think describe our different motivations and directions in life. Also, my sixth house focus has given me a great concern with health, which he shares only partially. I have wondered about the idea that when brought up together, twins can "agree" to take on more of certain aspects in order to differentiate. I'm still thinking about this one.....Probably if I were to 'embody' a planet for him, it would be his 11H gemini moon and/or 3H scorpio Jupiter. For me, he would be 3H virgo mars and/or libra saturn.
In answer to Radu's original question, I do believe that the difference between us is adequately described in our natal charts. My argument is this: Small natal differences may prove more significant, or even be overemphasised, for twins. To some degree, twins have a very interesting opportunity to see what they may be capable of, given different choices!! (For example, I'm quite confident that I could have accumulated $1 mill in assets, had that been my orientation...) I suspect that twins who grow up apart, or even strangers with the same birth chart, may end up more eerily similar than twins who grow up together.
I've posted the charts below incase anyone would like a look
Him:
Me: