Well after seeing many places every palmists talk about lines change when you start changing your way of thinking . . . But actually i dont think like that . Here i will put my best reasons to satisfy everyone and will try to remove this confusion
Here are reasons behind it

1. Palmistry and astrology is works together , i meant if anyone is very good in palmistry he can predict future exactly like astrology do or even better than astrology. If someone says he/she can change destiny just via changing thought and can create new lines so what the significance of astrological reading. In my whole life of palmistry career i have never found anyone  who was able to change his destiny via changing his thought.
Actually development of thoughts starts when planet changes their positions from one house to other and the effect of that changes can be seen in your palm too but but but you should be very good palmist to know how planets defeating your way of thought. . . .

2. I have a case of my friend , he is having half saturn ring (that is the worst sign i have seen if found) , saturn ring gives the bad effects of saturn planet as every good palmist knows that . . . So i told  my friend to change his metallity so his line will get changed and  bad effect of this line will get minimized he tried doing his best , but again he failed to do continuously

3. Another guy , 17 years old school student shown his palm , his heart line was badly effected , also it was also showing he is not good in friendship , in relation management , having bad relation with his mother. So i told him try to make many friends , dont eight with his mommy many things will change . He also promised but i met after 7 days and found that he also failed doing this.

So what actually i meant you cant change the basic nature of person as you cant change three basic lines . Also if astrology and palmistry moves parlally than how you can change your destiny just via changing your thought. . .

If i am wrong put your comment on that thing . . . We can have good discussion

Well what actually i wanted to say you didnt read it properly. . . For me my prediction method is not always based on lines. I mostly rely on planets position on palm. . . . Lines change according to the planets position
For example if i consider myself , 5 years ago i  had no sun line, now i have 2 long sun line and 2 long luck line. . . .
But at that age i was new to palmistry had very basic knowledge. Now after 5 years of my study i realised how palm lines change. . .
Palm lines change only when a planet transition takes place , and that transition of planet can be seen in your palm too but for that you need to have very deep knowledge to see how planets moving in your palm. . . The effect of that transition changes lines , lines does not change via changing thoughts thats what i meant

The book by Ghanshyam Birla Singh is indeed a very good book on the subject of palmistry.  You are correct that there are cycles which are guided by the planetary bodies, for example the seasons are a very good example.  Since our spirit is actually composed of influences from these planetary bodies, thus they do influence a mans being.  However, our behavior is also an integral part in our future.  Although the sun sends it rays, it is up to a man to be able to receive and make use of it.  

However, the topic you are talking about seems more relevant to the topic of free will vs. predetermined future.  I think you are suggesting that a man has no control over his future, and that he is guided by forces he has no control off.  But it must be obvious to you that you have full control over your behavior, you can walk and talk as you please you are not forced to perform any actions by some force.    Palmistry was of course founded by the holy rishi's who used to live in India.  They founded it upon principles such as reincarnation and karma, and they used it as a means to reach into the spiritual world, which is why they did things such as meditation and yoga also.  Their belief was that a man was like a magnet and was attracted to certain situations, that his spirit was attracted to certain situations.  For example, a man who made fun of and picked on others would contain that energy, and that energy would transform into a weak body in his next life.  Such a man would be picked on by others just as he had done in the past, but of course the man has free will.  A man who is picked on usually contains the energy of wanting to grow bigger and pick on others.  However, here is his free will he can choose to pick on others thus perpetuating the cycle, or he can forgive those who have picked on him and cleanse his karma.  The events that occur in a mans life are simply the return of energy back onto a person.  A man who is rich was poor before, a man who is good looking was ugly before, this was of course the doctrine of the holy rishi's and it was of course re iterated later by the Buddha.  I am of course re iterating the doctrine of men i mentioned, and it is up to you to believe whatever you want.    

If you were to study the ancient hindu texts, or even if you study kabbalah they mention the different worlds.  That there is a causal world, astral world, physical world and so on and so forth, and both maintain that mans thought founds the causal world.  If you were to study heremetic philosophy they also maintain the same thing, or even the famous book and movie called "the secret."  It claims that a man's thoughts are the founders of his reality and the physical world he perceives.  This is my belief, you do not have to believe it, you are free to believe what you want.

Well solisil

I not am disagree with your words whatever you told and the information is very helpful too. . . . .

But now what you need to do is practical , but for that you need great knowledge of palmistry specially mounts of palm . . . So first you need to start telling future of your friends with palm,   year and month wise ,and now use his birthchart  to predict his prediction using transition of planets you will always find it exactly matching because i have done it many times on many ppl . . .

Another thing according to astrology every person having different behaviour , different eye colors, hair color , lips  structure, chin , cheeks , nose ,because of the  of planets on his life. . . . For example if someone is having great effect of moon on his life he looks great, innocent , child like body skin, attractive face , small height . . . Also his behaviour is also governed by moon
But in palmistry you need to find the prominent planet on palm(its not easy to do without great practice) than which planet is evil effect on his life , which is having medium effect and many other factors .

So after deep analysis you can say palmistry and astrology is parallel to each other

Also you talked about reincarnation and effect of karma on palm but in astrology , astrologers also believe on it not only in palmistry .  But who bothers about past birth everyone live in present and they are not worried about next birth . . . .

I didnt read the book of  Mr. Birla as i never wanted to read it because to learn palmistry is not reading books you need to read palms and create your database.

So if we say someone can brainwash your brain and he can change your line then you will must find signs in your birthchart also in palmistry that someone is going to effect his life badly. Our palmistry knowledge is still not that sharp that we can know it but we can try our best to do