  The great influence of Bitcoin has promoted the rapid development of
blockchain-based digital currencies, especially the altcoins, since 2013.
However, most altcoins share similar source codes, resulting in concerns about
code innovations. In this paper, an empirical study on existing altcoins is
carried out to offer a thorough understanding of various aspects associated
with altcoin innovations. Firstly, we construct the dataset of altcoins,
including source code repositories, GitHub fork relations, and market
capitalizations (cap). Then, we analyze the altcoin innovations from the
perspective of source code similarities. The results demonstrate that more than
85% of altcoin repositories present high code similarities. Next, a temporal
clustering algorithm is proposed to mine the inheritance relationship among
various altcoins. The family pedigrees of altcoin are constructed, in which the
altcoin presents similar evolution features as biology, such as power-law in
family size, variety in family evolution, etc. Finally, we investigate the
correlation between code innovations and market capitalization. Although we
fail to predict the price of altcoins based on their code similarities, the
results show that altcoins with higher innovations reflect better market
prospects.
