How are David and Joseph Storm similar in The Chrysalids?

The similarities between David and Joseph Strorm are far from obvious. This is partly because David is able to distance himself from his father's ideals in his narration, and partly because, as David suggests, there is a big gap between his generation and his parent's.

In my father's childhood mothers used to quieten and awe troublesome infants by threatening: "Be good now, or I'll fetch Old Maggie from the Fringes to you... Nowadays, however, it was not only small children who lived in nervous awareness of the Fringes people not so far away. Their existence had become a dangerous nuisance and their depredation the cause of many representations to the Government in Rigo.

David's father had grown up with very little to contradict the strong views that David states were instilled in to him by his preacher father.

Grandfather Elias had never a moment's doubt of the proper pattern for his heir. My father's faith was bred into his bones, his principles were his sinews, and both responded to a mind richly stored with examples from the Bible, and from Nicholson's Repentances. In faith father and son were at one; the differences between them was only in approach; the evangelical flash did not appear in my father's eyes; his virtue was more legalistic.

He had even gone out his way to marry a woman whose views

harmonized with his own... [my mother] had a strong sense of duty, and never doubted where it lay.

David is more or less left to own devices, which gives him the freedom to meet so called mutants and question the nature of the world he's living in. Of course David shares skills with his father such as leadership, but his comparative freedom gives him the opportunity to access parts of himself that his father never had the chance to. It is perhaps similar in vein to the generation gap felt in the 50s and 60s between the prewar and postwar generations.

On a literal level, David and Joseph Strorm are genetically similar.  They are father and son, so they share quite a few genetic traits.  That sounds like a cheap answer, but considering the Waknuk's emphasis on keeping genetic mutations out of their society, it is quite important.  Genetic similarities are highly sought after in Waknuk society.  

Both characters are strong, alpha type leaders.  Joseph Strorm is a well known and respected leader in the Waknuk society.  People look to him for leadership.  The same came be said about David as well.  David becomes the leader of the telepathic children, and they all defer to his decisions about what they should do and when.  

Both characters have strong opinions about things, and both characters act on those opinions.  Joseph believes in keeping the Waknuks pure, and he goes about it with religious zeal.  David doesn't believe in what his father believes in, but David does defiantly stand up for his beliefs.  He does this when he keeps Sophie's secret about having six toes.  In a sense, he is protecting her right to live.  He also continues to fight for his own right to survive along with all of the other telepaths.  

What are two characteristics of Joseph Storm in "The Chrysalids"?

Joseph Storm is the father of David, Mary, and Petra.  He is not a nice guy.  Kind of has a "holier than thou" type attitude.  He does believe that he is a man of God, but the reader learns to think otherwise.  While Biblical scripture does at times show God to be an angry God (think Sodom and Gomorra), the Bible also describes God as a loving father that expresses forgiveness and love constantly.  Joseph Storm, on the other hand, is quite unforgiving.  It is his way, or no way at all.  He has a quick temper and violent tendencies.  Those two things together make him cold hearted toward anybody not in line with his way of thinking.  For example, he beat David for suggesting that he could tie something better if he had another hand.